You can actually spray baste your sandwich on a wall.....standing up if you like. Use the search feature at the top of the page, there are several threads to tell you how to do it.
On the quilting of this one...I usually do all the quilting in the ditch first with a monofilament thread on the top..then I go back and do the rest of the quilt. You might consider changing your method to "quilt as you go" or quilting in sections for your next quilt.
You can do this...there are lots of ways to accomplish it and they are ALL correct! :D