With a pencil lay out the area to be removed.
Tools required to cut the posts are:
circular saw
reciprocating saw
Use a chisel and block plane to clean up the cuts. It takes about 10 minutes per post.
Rona or HD doesn't stock the LVL's. Go to the contractor desk and order them. I think they'll round up the size to the nearest 6" and give you about 1/2" extra length to square off each end. There are a lot of different sizes available.