You are right about some dark colors transferring - even after being gently washed once. (Experience speaking here! )

You are lucky to be able to have a spare bed to lay them out on. That is probably "the best" way to store them. Assuming you do not have cats that think that any horizontal surface is theirs! (lol).

My cats seemed to have a "hair release button" that activated as soon as they got near anything made of fabric.

I have a dozen or more quilts stacked on a bed in my guest room. I have nothing separating them and did not see a need to do so. I use a lot of bleached muslin and love it to back quilts. I don't pre-wash it either. I do use it washed however and set it with pot ash if I am going to die the fabric. That of course is another topic all together.
It is easy to show off quilts this way or move the majority if having a guest over night.

Again, thanks to all the people who replied to my questions!
I found out something. Cheap, 100% cotton sheets do not exist! lol
After spending over 100 dollars on that roll of muslin, I had to try something else.
Nail Polish!
After cutting the muslin, I put a little nail polish on the cuts, let it dry overnight, washed and dried, no fraying at all!

I have the majority of my quilts stored in an open shelf cupboard. I do not put anything between them, but do put a piece of fabric on the shelf bottom before putting the first quilt down. I've done this for years and have not noticed any fading, etc. I do take them out every so often and refold or display on my bed for awhile. The cupboard is in a darker corner of my living room so is not getting direct light. Hope you find what works for you.