3 man mechanics, Tip goes long
 

Opening tip. The ball goes deep to U2's end of the court. The ball is controlled by white, who is going the opposite way (they have recovered the ball in their backcourt.) U2 becomes the Trail and brings the play to the front court.

Question- does the R become the lead and go to the baseline and U1 become the center? Or the other way around?

It has become acceptable to have the U2 (or U1) to start a count and bring the ball up the court like a trail, but then move to center after they have a count. The U2 (or U1) must be sure they take the ball because they are standing right there. After everything is in the front court, you move to the normal positions. This might be something you want to pre-game to be sure. But as a rule, the R is still the Trail by all means at the start.

Peace

If there's a deep tip followed by a press, the coverage might have to be changed.

For some reason, this happens less than 1% of the time -- even with teams that press on other posessions.

I've never done this, never seen it done.

U1 goes the L, R drops in behind to L, C counts.

R slides to Trail, I think you mean to say.

What I have seen and what I usually pre-game is that if that happens we get set (quickly) and then rotate. That way the counting official is now the T and the R is now the C.

Check local listings.