For quick and easy attachment, try the new stuff from Loctite, I think it's called Quickset.
I used it last week, attaching 2" foam to 1" x 3"s on a friend's layout. As mentioned for the Liquid Nails product, be sure to get the one for foam.
I glued down six 8' sections down, weighting them with boxes, to hold them in place. After three section, I was able to move the boxes from the first piece to use on the fourth. The glue was set and the foam firmly in place. The time frame was about 40 minutes.
The Loctite Quickset does scim over pretty fast, so don't take too much time before putting the foam in place. Once in place, move it around slightly for good adhesion.
I'm a big fan of latex caulk. I use it for virtually everything (track to roadbed (I use rope caulk for roadbed - it's nice and quiet and works REAL well.....cheap too!), roadbed to suroadbed, foam to plywood, everything). Get the cheap stuff and make sure it doesn't attack foam. Use a putty knife to spread it real thin (you don't want it coming up between the ties) and then grab a few old MRR magazines and set them on top. Now go have a nice relaxing dinner and when you come back a lot of times the caulk is holding well enough to make a test run. Once you're satisfied, set the mags back and come back in the morning. By that time you can run trains to your hearts content. It goes pretty quick once you get the hang of it. I laid a 4 track staging yard (15' long) and a reverse loop in about 30-40 minutes.
I tried liquid nails and didn't like it because once it dries if you want to make a change you destroy the track and the surrounding scenery in the process of removal. Also, liquid nails dries hard, so it amplifies sound. Caulk doesn't dry hard so I think the sound level is better.
Whith latex caulk all you do is slip a putty knife between the rails and the roadbed (or roadbed / subroadbed or hatever) and gently pry up. The rails come up undamaged and completely reusable. Almost my entire staging yard on the layout I'm building now is made of reused rail.
HO getting ready to clue or cement a 2 foot x 8 Foot section of 2 inch blue foam to 1/4 inch plywood for a self layout. What is the strongest and the best and fastest adhesive to do this with. I have found in the past the Carpenders glue works good. Will it completely dry between the layers. Need a real strong bond all over in case its moved.
Thanks for your help, DON