They give tenants permission to contact those individuals directly any time they are unavailable.

I really wouldn't care, but when you have a homeowner losing their home because they're caught up in a contract with someone who has a clause that says the contract is subject-to finding an end buyer & gives them permission to market the property it's no different than a contract that's subject-to flipping 3 keys of coke & finding a cheaper distributer. 

They asked for my permission to add some landscaping to the yard.

There may be ethical reasons to not assign a contract (my personal opinion is that (1) if the contract provides seller financing or other terms that rely on the performance of the buyer after the closing, it is unethical to switch buyers without the seller's permission or (2) if you haven't properly vetted the assignee or used language to prevent them from also assigning to someone who can't perform and you are not able to close if they fail to, that is not fair to the seller) but that is a personal opinion not a legal distinction.I'd be interested in taking assignment of your contract if it is a truly profitable deal. 

But if someone lives in the property, you need permission.

They are allowed to sign or move.From your explanation, the tenant "seems to have invited other people" means you don't know if they already have permission to be there.

If there is nothing in our HOAs about short term rentals, do we still need to ask permission to start one?

what do i do with all this junk inside the house and personal property can i throw it out without the previous owners permission or must i contact them about it?

Get permission from the lender to transfer the property to the LLC in order to make sure the "due on sale" clause isn't violated.  

I also ask other questions that cozy & mysmart move do not ask.if you want something that just is a form and gets their permission Wufoo.com is free form creator that will send the form answers to your email.