Join HSLDA, Home School Legal Defense Association first.
http://www.hslda.org/Default.asp?bhcp=1
It's about $100 a year and they'll provide all legal assistance you need for that fee should you need it, provided you join BEFORE you have trouble. It's not a lot of money and great for peace of mind.
The other option, and I don't know how this works for PA, is to connect with a Christian school that has a homeschool program. With those programes, you are under the direction of the school and meet there once a week for classes like art, gym, etc. but do the teaching yourself at home the other days of the week. That way you're officially registered at school and can avoid the paperwork and coming onto their radar. It works for some.
We're definitely going to join HSLDA. I haven't finished reading through their site yet, but they seem to be a valuable and necessary resource for homeschoolers, no matter what state you live in.
Right now, I'm researching groups in the area. I'd like to "join" other homeschooling families, for support/advice, fun, teaching, etc. I only found one organization on HSLDA, right in the township we're moving to, the Buxmont Christian Education Institute, which seems to serve as something for grades 9-12 (testing, diplomas, etc), so that won't work for awhile!
I ended up searching over at Yahoo groups, and may have found a less formal group of homeschooling families. I won't know until we make the move, and I can meet them.