Thank you very much!

Hello and Merry Christmas.

I have a Christmas Village that I put on a folding table.  The table is 6 feet long and 2.5 feet wide.  I would like to have a train that makes an oval loop around the outside of the table, with the village pieces on the inside of the loop.  I was thinking of going with HO gauge, but would like input on if that is the right size, or if I need to go smaller to be able to make the turns properly.  Additionally, I do not think that the train sets come with enough track to accomplish my goal.  I am guessing that I simply order additional track pieces when I order the set?  Lastly, can these trains operate on a 2 level track?  By that I mean, can I have the track go up and over the lower part of the track, or is it best to have it all one level?