Doubt it since they skipped the Spring ECLSTS earlier this year.

-Brian

The Big Hauler line has been made for about 20 years.
Depending on the age, condition and rarity (usually not much of a factor) used sets go for $40 on the low end to over a $100 on the high end. The older the loco the less its value as the earlier versions had weaker gearing (there have been 5 versions of the drivetrain in the loco).
Loco Bill can give you more precise info on the vintage of the set.

-Brian

That's Small Scale Railways - http://www.smallscalerailway.com/
They have a Huckleberry RR 4-6-0 sound card that should be a good fit. I have one of there other cards which I like. They only thing I would advise is to add extra shielding around the optical sensor for outdoor use.

-Brian

I have used the Ozark ones - http://www.ozarkminiatures.com/scripts/prodView.asp?idproduct=121

-Brian

Yes, they will fit without a problem. They are just a touch larger in diameter than Aristo wheels.

-Brian

Nope.

Is this like the question -
How many licks does it take to get to the center of a tootsie pop?




-Brian 

You can get a nice wood replacement from Banta - http://www.bantamodelworks.com/T2085.htm



-Brian

Kevin reviewed it here - http://www.trains.com/grw/default.aspx?c=a&id=1161
You'll need strip out the existing board and use a small pack like this one -
http://www.all-battery.com/li-ion1865074v2600mahbatterypcbmodulewith22awgbareleadsandhitecconnector.aspx
I get better than 5 hours of run time from the 11.1v 2.2Ah versions of these.
I use the trailer car option with simple (non RC) control-





-Brian

Small wheels typically on the two axle ore cars and such -



Here are a small wheels on the BH ore car with Delton trucks for a special project -



-Brian

I have never heard of that and have used ordinary rattle can spray paints on Big Hauler cars and locos without a problem.

-Brian

It looks more like the Spectrum mogul with a straight line boiler. Would make for a good bash project.





-Brian

I'll second that. The Knox & Kane #58 will be a decent match up for the K-27.
I would suggest adding extra shielding around the optical sensor as outdoor conditions can sometimes confuse it. A plastic cup with a small vent mounted on the back side of the speaker will great improve performance. Also it will need batteries to run off of. I would suggest a couple of 3.7v Li ion cells (for 7.2v) like these - http://www.all-battery.com/2li-ion1865037v2200mahcellswithprotectionpcbwithtl100li-ionuniversalbatterycharger.aspx
will let you run all day and then some.

-Brian

and maybe some of us are just offering advice to avoid the mistakes we and our friends have made. 
Another thing about the Bachmann track, since it is hollow it can be pretty noisy to run on.

-Brian

The Bachmann track is fine for temporary layouts around the Christmas tree but for long term, daily use I would invest in brass track. Bachmann track is hollow tinplate (not terrible strong) and gets dirty pretty quickly. Brass track is available from AristoCraft, USA Trains and Piko.

-Brian