Good paying, long term tenants are worth their weight in gold! 

I got a got a business line of credit to my LLC secured with the equity in my rental.

Other option is to "trust" and wait, which would mean that I am taking a risk and would have to tap into security deposit if things go ugly. 2.

How would you proceed to secure this deal?

I haven't secured any loans from anyone before so I'm not sure if I should try to get the lower rate on the majority of the price and hard money on the down payment?

There are also services that will keep your collateral files secure for a fee, so that may also be a good option. 

A Nice SFH house for yourself is a dead weight if your starting to scale and just the two of you.  

Walls may be weight bearing?

If this is the case, then do an inspection to verify it is vacant and in good condition prior to any money changing hands.Make sure the security deposits and prorated rents are transferred to you.

Think of all the things that could go wrong and see if the lease addresses them: unauthorized pets or tenants, early termination, security deposit, lease violations, late rent, eviction, lawn maintenance, parking, etc.5.