You do not own that developing place right now. You only own a right to the title upon completion. I don't believe any creditors would give you loans against it for that reason. It is officially not yours yet.
as for assignments, you are basically transfering that right to get the place. The assignee still won't own the place until completion and if they fail to fulfill on the final payments you are still liable. Many people think once they've assigned they are scott free, and this is not the case. Also, there is restrictions to advertising assignments, periods for doing assignments and usually fees for assignments. Something like 1.5% of the purchase price but it varies.
check the assignment section in the addendum to your contract for more details about your specific contract.
I do assignments/contract stuff for a presales company, so feel free to PM me if you have any specific questions about your contract.
which developement is it by the way? I may even have your contract in my office and know everything about you.
(insert evil laugh)