Is this generally a win or a draw?  What drawing or winning techniques are there?

I think it's a draw. Technique: don't blunder.

I mean a win for the three minors or not, in case you thought a win for the rook.

It is quite obvious the rook will not win (unless there are a lot of blunders).

BTW when I said it's a draw, that is a very rough guess. I think if the three minors can force a win, it could easily take dozens of moves. The 50-move rule would be of utmost importance.

Endgame tablebases seem to say that surprisingly, two bishops and a knight can usually win against a rook, but two knights and a bishop usually only draw. This makes some sort of sense: if the rook is swapped off for a bishop, we want to be left with B+N which wins and not N+N which only draws.

As for techinque, I have no idea- scrolling through a random tablebase win, it looks like White plays for a standard two-bishop checkmate, while mainly using the knight to block checks from the rook. I wouldn't bet money on being able to win this endgame over the board, though.

Wow; I was using the analysis board to see what I think, but I was doing it with two knights and a bishop. I reverse my previous guess.

Two knights and a bishop almost always draw, but two bishops and a knight can win, since there the rook cannot simply sacrifice itself for a bishop.

This endgame actually occurred in one of the Karpov-Kasparov games (from a tournament).

what was position?

http://www.chessgames.com/perl/chessgame?gid=1067317

the aforementioned karpov-kasparov game. 2 knights+1 bishop vs rook