Hi I own the 107's and the 104.2. The latter is being done now by a professional. They are the butyl rubber surrounds with the foam inner annulus. The 107's I think were all foam, no butyl rubber surrounds. Yes, you can do the new foam ones your self. There are excellent step by step instructions available online. Remember to do the outer foams first. You will have to cut out/remove the inner ones so that you can shim the cone before attaching the outer surround. Finish by glueing in the inner foam annulus.
Yes, one out of the bottom, one out of the top. While you're in there check out the caps in the X-Overs. Any electrolytics that are 15-20 years old and 15% or more out of range should be replaced. It's probably good to replace all the caps that are that old if you really want to do it right.
They will sound awesome again. Some of the finest speakers ever made.