First ever venture into Armor

Airfix used to do some nice modern US troops in 72nd, you might have to try E bay for those. Your only other option is Revell.

http://www.hannants.co.uk/product/RV2520

These are rather nice as well.

Vinyl tracks typically have pins on one end and holes on the other. The pins are inserted throught the holes and melted to make them too wide to go back through the holes. Some newer kits have tracks that can be glued with model cement. I'm not familiar with the small scale Trumpeter kits. Vinyl tracks are usually long enough to fit snug on the wheels without any cement. Track sag isn't an issue on the two kits you have because they both run with a tight track. If you want sag there are some tricks to getting vinyl tracks to sag, but the easiest way is to use individual link tracks or link and length with the sag molded in.

Roadwheels are a pain in the butt most of the time. There are about as many ways to do them as there are modelers. On a brail scale kit you might try using a dark heavy wash on the road wheels rather than trying to paint the little devils. The tracks on both your kits have metal and rubber parts. The rubber would be a gray black color and the metal can be anything from rust red to shiny steel depending on your operational setting. Try doing a search on the internet, there are tons of color photos available to give you an idea of what they should look like.

 I have no advice on 1/72 scale figures.

paintsniffer

Do they get the right [track] sag on their own or is there a trick?

How would you tell? The return path is under skirts! I’m pulling your leg… there is NO significant sag on either vehicle for any I’ve seen. If you want sag, go Soviet. I’ve got this 1:72 IS-3 in my queue…