>>685118
>Is God separate from creation?
Define "separate".
Any similarity between Creator and Creation is far less than difference between them. But created human nature can be divinized and is in fact united to Divine Person.
>Is the creation filled with God or is creation inside God?
God is not body therefore you cannot technically say that creation is filled with/inside of God, strictly speaking. Rather he is present. To quote Augustine.
Nevertheless, he is not distributed through space by size so that half of him should be in half the world and half in the other half of it. He is wholly present in all of it in such wise as to be wholly in heaven alone and wholly in the earth alone and wholly in heaven and earth together; not confined in any place, but wholly in himself everywhere.
>If creation and God are separate is he really omnipresent? Doesn't that then make him finite since he has separation?
God is not present in corporal way.
>And if creation is in God why is it so fallen?
God is not creation, creation is not God.
Also, do yourself a favor and read first part of Summa.