Hey there! I'll try my best to help you with biology but it's been a while since I've done any so please excuse any mistakes! :)
So there are two kinds of traits, dominate and recessive! Dominate is the strong one and will show up more likely while recessive is the unlikely one. I just looked it up and found out that not being able to roll your tongue is recessive so the parents have little "r"s like this rr.
1. None because there are no big "r's (look into Mendel's squares to understand what I mean).
2. I believe none as well.
3. It is going to be rr (genotype is either RR, Rr, or rr)
Again, I might not have everything exact but I hope I was helpful!
- mathwizzad3
