I've only done a few.......here's what I've noticed.
Much is negoitable. Many times the guidelines are the same as traditional transactions except: seller contributions (none), home warranties (none), repairs (none). They will usually allow 3% towards buyers closing costs, and pay regular real estate commissions with co-operating brokers involved. They may try to reduce commission on intra - office transaction.
Most lenders will pay delinquent property taxes but will not pay delinquent HOA dues.
If I were buying, I would start by disputing the lender BPO. A BPO is just a cheap desktop review of the property. Someone more knowledgeable with the subject property and the area can generally present a convincing case either positive or negative. You can usually get the numbers to say anything you want them to say. Start by getting them to say that the home is worth less. Much less. Make them fight to prove their price. Especially if there is no buying frenzy on the transaction.
Make the value of the home depreciate right before their eyes. Turn in repair estimates with your offer. They need to see the property as a hot potatoe. Sometimes with these lenders it seems like your shooting at a moving target. Make the target move in your direction.
Never show them you have more money than what's needed for the transaction. You know the song, "know when to hold dem, know when to fold dem, know when to walk away, know when to run...LOL."
Try not to over qualify for lending if financing.
Good Luck!