tracks ahead has been on the air on pbs for many years now. i believe it is sponsored by kalbach publishing (model railroader) and walthers.

you can think of it another way. the manufacturer(s) who made the $20 locomotives that lasted an hour is/are no longer making them. they either went out of the train business, or upgraded the quality of their line. put out junk to-day, and you get roasted alive by the serious model railroaders. some companies are still trying to live down the reputation they got 30 years ago.....

in both n and ho, the overall quality of the stuff out there is light years ahead of what it was. knuckle couplers and metal wheels are pretty much standard now, just a few short years ago they were both aftermarket upgrades.....

HO used to be the cheapest, but in the past 10 years or so, N scale has them beat.

to clarify the above posts. rp25 is the standard set by the NMRA for wheelsets. 33" and 36" are the wheel diameters, in scale inches. they correspond to the wheel sizes of the prototype wheels.

to answer your questions:

1. yes, the two main bus wires are connected to your power supply

2. i have always soldered my feeders to both the rails, and to the bus.  soldered connections are less liable to corrode, if done properly, than mechanical connections like terminal strips. and if you wrap the joints where your feeders are soldered to the bus wires, they won't accidentally short out either.

terminal strips are readily available at radio shack. as bob said, they have screw type terminals similar to your power supply. you may also want to use bus bars, which jumper the adjacent terminals on a terminal strip together. that way, you can use only one wire per screw which gives a much better connection.

http://www.radioshack.com/product/index.jsp?productId=2103982
http://www.radioshack.com/product/index.jsp?productId=2103227

note that the bus bar jumpers can be trimmed to whatever size you need with a set of cutting pliers.

two things to watch for when wiring. first of all, make sure you are connecting all the feeders from the same rail to the same bus wire. if you get your wires crossed you have a dead short and can fry your power supply. a paint marker or a piece of tape is a good way to mark things to ensure that you don't get your wires crossed. second, for safety's sake, i'd recommend each bus wire have its own seperate terminal strip.

3. it doesn't matter whether your locomotives are dc or dcc they still draw power on a dcc system.

4. by all means go ahead and order your parts. do not be afraid to tackle this job.  you don't have to bae an electirician to wire your layout. i've been doing it since i was about 12. as long as you mark all your wires and don't get them crossed you will be fine. in fact, i'd hook up one set of feeders at a time them run your train on that track to make sure everything works.

how do you listen to the sound files on the digitrax site?

i second bob's opinion that you have more than enough power for the layout.

i had a similar layout, 13.5 feet per side, l shaped, 3 or 3 track mainline with branches and 2 yards. my wiring was all 18 guage, including all feeders. i had at least one set of feeders to each track, every 6 feet or so. and i was using the zephyr as my command station, it put out 2.5 amps, hlaf what you have. i experienced no degradation of performance running multiple trains, even though my layout was wired below recommendations (smaller wire equals more resistance and in theory less power on the rails) and a lower powered dcc system.

power feeders weren't as much of an issue with the older dc packs, because each train would be drawing it's power from a seperate power supply. with dcc all are drawing power from the same source.

my question for you concerns your locomotives. you mentioned athearn< how old are these? older athearn motors, those used before 1980 for sure, were notorious power hogs. some drew up to an amp apiece under normal circumstances, and up to 3 amps stalled. these ywould be the ones with the big wraparound magnet than were somewhat round in shape, not the later flat sided motors.....

another question, do you have locomtives parked on live tracks when running your trains? on dcc every locomotive draws power whether it is running or not. if you have alot of locomotives sitting around a turntable area, for example, you may want to add a seperate booster supply for that area......

lighting for locomotives is drawn from the track power. it is possible usiing dcc to turn the headlights on and off, but they are still using track power.

the mrc sound decoder marketed for the atlas s2 is a very good rendition of an alco 244 engine, which unfortunately wasnt used in the s2/s4. it is, however, an excellent choice for rs2, rs3, rsd5, fa1 or fa2.

one of the sound decoder manufacturers, i think it is QSI, offers downloadable sound files for their decoders. from the samples i heard, they are quite accurate.

soundtraxx offers an EMD 567 decoder that is dead on for any of the f series units, and gp7s and gp9s as well. they also have an EMD 645 decoder which is close but sounds a little off to me. it would be appropriate for gp40 and sd40-2.

for reference, here are the sounds you are looking for:
gp40 & sd40-2 use the same engine block and thus sound the same. they both use an EMD 645, 16 cylinders, turbocharged.
the ft uses an EMD 567, 16 cylinder, non turbocharged, also sometimes called normally aspirated or roots blower.

rectifiers will only change ac to dc, not dc to ac. an inverter is needed to change dc to ac.

it sounds like you may have a bind in the drive somewhere, to find it you must take the locomotive apart.
start by removing the body shell and turning the motor by hand. if it hangs up anywhere you have a bind. often this will be caused by something getting into the gears. remove the trucks from the frame, and remove the worm gear from the top of the truck. the truck should roll freely at this point, if it doesn't you've isolated the problem. completely disassemble the truck and check each gear for foreign material in the teeth. remove any you find, put it all back together and lightly lube the worm gears. running the locomotive will ensure that the lube is psread through all the gears.

your lighting should work on dc as well as ac. and you'd have the added advantage of being able to dim your lights.

the big problem here is not that the rails on the two routes through the crossing are not electrically seperate. they are i am 99% sure, as not having them seperate greatly complicates wiring the crossing. it wouldn't be EZ then would it?....lol

the problem, which was common on earlier makes of switches, is that there may not be enough insulation where the rails cross to keep the wheels from bridging the gap. like i said, this causes a momentary short which is not noticable on dc but wreaks havoc on dcc. and dc and dcc do not play well together.

this problem is not one that an ohmmeter will detect. the only sure way to detect it is to carefully watch the wheels of your trains as they slowly run through the crossing. if the wheels even LOOK like they are touching the metal rails on the opposing route, do NOT use the crossing unless you are running either all dc or all dcc.