Great reading! I'm glad to hear that 'non-longarmers' are open to suggestions for improvement from longarmers. I would never want to hurt anyone's feelings.
I would like to suggest that making a square top does not start when the blocks are all put together. It begins with the very first piecing in the block. If each section of a 12" block is off 1/8" that block is not going to be 12" when placed in a quilt top. If some of the blocks measure 12" and some 12 1/2"...you're quilt will most likely not be square and you got some ripping to do! Remember to measure as you go!
With borders my biggest recommendation would be to remember to measure the quilt top in 3 places and average it out. "Ease" the border to the quilt top. I've had customers add in 1/2" of border to make the border fit. If they had 'eased' it in, the border would have looked nicer without a small 1/2" piece of fabric sewn into the border.
Bonnie Hunter has a nice tut -
http://www.quiltville.com/borderhints.shtml I'm sure there are a lot of other tuts available.
Happy Quilting!