best friends?

Everyone rushing is given a group number. There are RCs (Recruitment Counselors) assigned to lead your group around to each house for the first round. So unless your friends are in your group, yes, you will be split from them for the first two days.

After the first round, everyone's schedule is different so there's no touring in a group. You're pretty free to walk around between parties and visit with your friends (if you have time).

Some people have friends rushing, some people don't. Unless you tell people in the chapters that you have no other friends rushing, I don't see how they'd know. I honestly don't think they'd care either way.