For any of it, go around the rails lightly with an ink eraser or those abrasive sponge things,
just one or two passes, to clean the rails.
The old Tyco and AHM locos did not run well when new, so don't be disappointed if they run
rough, or not at all.
Since the turns will be tight, for your proposed usage, don't buy a 6-axle loco, instead buy
4 axle. You won't be running DCC (Digital Command Control), so make sure the loco is
not decoder equipped. Will probably say "DCC ready". Tell the hobby shop you will be
using DC, not DCC.
There may be a coupler incompatibility issue... older cars and locos almost invariably had
"NMRA horn-hook" couplers. Most all currently made stuff for the past 15-20 years come with
Kadee compatible couplers. You may have to make an adapter car with a horn-hook on one
end, and Kadee on the other. Get the hobby shop owner to assist you on this.
Another vote here, for you, for the Bachmann EZ-Track. Kato is very expensive and I rarely
see it in shops. The Atlas track with roadbed is good also, but rare. EZ-Track is the most
common track with roadbed you will find.
Some tire balancing weights, the little square or rectangular ones with sticky adhesive will
help keep the cars on the rails. Shorter cars (40'), 4 oz total weight, medium length cars
(50'-60'), 5-6 oz total weight. Place the weight as low in the car as practical... on the floor
of boxcars, in gondolas, hide them under loads. etc.