Hi Jeremy--I'm seeming to have the same issues as you
I have one hive that is making a wavy mess, another hive that seems to have some built directly next to the guide.
So, I don't have much experience, but I'll pass on what I've heard.
1. Brush the bees off with your brush. I'm thinking an upwards or sideways motion might help reduce pressure on the comb-attachment point and help prevent this fresh wax from breaking off.
2. Aren't you planning to tie them in on center? Then, the presence of the other centered combs around them will keep them centered, too. In fact, last week I stuck in open bars between comb that had been built on center (the guide). The new combs between these are built on the guide, too.
3. I have heard that the bees chew out and get rid of the rubber bands once they've fixed the attachment at the top. We'll see
4. I, too, will have to find REALLY big rubber bands that will hold the comb in place without crushing it. I'm thinking some sort of office supply store...
Good luck! It will be great to hear how this goes for you!