Secured to the foam, my track is moslty just "pinned" with screws; as in only a few actually enter the wood below the foam. Screws because with threads, they are less likely to work their way up than a smooth nail/tack/pin.
Where they do enter wood, the solid connection's tendancy to telegraph sounds makes it louder.
Pinning works well since shifting sideways is what you really want to prevent. Screwing it down tight is only really needed if you plan on turning the layout on it's side.
I couldn't find homesote. I began with the foam loose on the wood, but it drummed pretty bad. I used foam board adheasive, which is pretty rubbery; it helped a lot. I chose pink foam because it could handle my palms and with a small 5x5 piece of paneling, my knees and full weight (about 200lbs, usually under)
Felt used to be awesome. But finding that isn't as easy anymore. Carpet and cloth, like a thick towel is the best I've encountered; but I haven't figured out a real good way to utilize it well where realistic scenery is used too.
My thoughts so far are that layering would be effective. Cloth glued to, and between some plywood would stop telegraphed sounds to the frame & lower base wood, leaving only reflective noise off the top wood. Lots of ground cover will eat the reflective sounds before it can bounce. Attaching solidly to just the top plywood at that point shouldn't transmit sound very well at all; just the reflective sounds remain.
The big issue with cloth is drilling holes without the bit grabbing cloth is a big challenge. Either you need to drill and cut cloth ahead of gluing, or use partial drilling and then use a SHARP circle punch to cut the last bit of wood and cloth. (You can make one from tubing/pipe with a beveled edge, orHarbor Freight has sets pretty cheap )
