I have not read any of the responses yet, so I am probably repeating what many have said.
The best machine to take to a quilt camp or retreat is the one you feel most comfortable with. I sometimes take my Bernina 440QE, depending on what projects I plan to work on, but I also take my Singer 221 Featherweight, which I love for straight piecing and is at least 10 lbs. lighter than the Bernina. The FW is much more portable and makes the best straight stitch of any machine I own. However, I know many quilters who only have one machine, so be glad you have a choice.
I don't go to a quilt retreat to impress others or to be impressed. I go to sew. I enjoy laughing, talking and looking at the other ladies' projects. I always manage to learn something new and to teach something to someone else. Needle and thread sizes are dependent upon the project -- for piecing and paper piecing, I usually use an 80/12 needle. For quilting, I use a 90/14. I pretty much stay with one thread, 100% cotton Prescencia 60/3 in neutral colors. Most of the quilters I know piece with a 50/3 thread, which is what I used until I fell in love with the Prescencia. I was taught to match fabric and thread -- if you use 100% cotton fabric, use 100% cotton thread. But there is nothing to stop anyone from using C&C all purpose, which is cotton wrapped around a poly core.
There is nothing wrong with being a piecer. There are many in both guilds I belong to who "quilt by check". I myself was one until not too long ago, because I was intimidated by FMQ. I have taken several classes for quilting on a DSM, and have stepped out to quilting my wallhangings, tablerunners, placemats, etc. However, I haven't quite worked up the courage to tackle a bedsized quilt yet.
Remember, there are no quilt police. Don't let anyone tell you there's only one way to do something. Likewise, don't turn your nose up at anyone else, either. Quilting should be a joy, not a competition.