rook vs bishop all pawns present

Like this?

Yes

Move a couple of centre pawns, bring the king up (to a white square is simplest), if he moves any pawns two squares then use that to lever open a file(s), once you have open lines the position wins itself - also be on the lookout for any good opportunities to sacrifice the rook back for his bishop if that allows a transition into a trivially won pawn ending etc. 

Yes

Thank you. any tips on the vs knight one as well?

Install SF.

Watch how SF play against you or vs herself.

https://stockfishchess.org/

just checkmate with all pawns (possible?)

Just use that aspect of the position - say Black puts his pawn on (for example) d5, then white playing d4 (if he hasn't already) to fix it, followed by Rc1 and c2-c4 would force an opening of a file - in this case the c file. The more open lines there are, the more the rook will dominate.

Sure, watch SF try to win an endgame....

If you want to see technique so poor that it takes the machine 200 moves to do what a human can do in 20.

The basic mechanism is this:

In the beginning just push some pawns, activate your king, and then eventually you'll be looking for opportunities like the above.

Important for new players to observe is that usually the worst way to defend is to put your pawns on the same color as your bishop, because as we see in the above example, the white king is free to infiltrate to any square that he wants (black gave up the dark squares).

Activate your king as much as possible, activate your rook as much as possible, and pay attention to the weak pawns of both players. If the knight and king can't generate threats on your weak pawns (typically the base of a pawn chain), then it's only a matter of time before you win. Just maneuver to increase activity, look for zugzwang, and just like the R vs B be mindful of sacs that can generate passed pawns.

Sure, I didn't check it for accuracy, that may be best, I just wanted to show a basic idea.

whoa super helpful. i got some studying to do. thanks!