Matt,
What the sellers mean is the past buyer either found something on inspection,the bank took too long to reply to the short sale,or the buyers offer was too low and they didn't like the banks counter.
So short sale approved means the bank has ordered evaluations of the property and came to the conclusion this is what they would accept. Generally the sellers have no money in these situations.So the costs associated with the seller side the bank might balk at paying and you will have to come up with those funds.
The separate deed issue is a biggie as well.
Residential loans are single family properties,duplexes,tri's,and quad's.
Anything 5 units and above goes into commercial financing.Commercial financing the underwriting is much easier to qualify for as it's not regulated like the residential.
If the properties are separate legal description than most lenders will count them separately and not together.This will force you into a residential type lender. If it's one legal description you can count as 5 units or above.
They are some commercial lenders who will do if separate legal descriptions but the properties have to be together and the lenders are few and far between.
As gar as tenant inspections.Many times buyers just say insurance inspectors to take pictures so it doesn't spook them.If the seller has been a crappy landlord they won't mind new blood.
If the current landlord is awesome and their impression of you is not stellar they might high tail it out the door.
If the landlord has been self-managing it will make more of a difference.If property was managed by a company and you keep that company not much will change for the tenants.