Cloth Rendering issues and Cloth Colliders

Hello guys!
I am very new in Unity, actually i just do my art project in it.
I have about 30-40 planes which are actually cloth objects with gravity that i need to hang in different ways on dryers and ropes (scene with clothes that are been drying outdoor).
The first problem is after 5-10 sec I start to play, there is rendering issues with the clothes - they actually dissapear in some view, and also making very strange motions they should not (like a mesh problem)- and only after 5-10 sec they are back. Clothes are actually main objects in the project so need to see all of them and all their motions (wind, gravity) in my camera view and the motions should be natural.
The second thing is that i need to have the floor as a collider, i need to have clothes that can fall down to the floor but there is only sphere and capsule collider for it and I cant use it for the floor. Also, is it possible to make the cloth object to intersect itself somehow? It would help a lot.
P.S. I know about Obi, but I am not able to change it so that I could use it to my objects. Is there any easier way? Thank you

Sorry I meant to make clothes NOT to intesect itself.