Although she told me this under the assumption I would make a cash offer and handle all closing cost, I figured it'd be worth asking her would she be ok with me purchasing the property with traditional financing and she pay SOME closing cost (half of the 4% philly transfer tax). 

@William Hughes your assumption is correct.

Has done seller-financing, mortg assumption, and QoF for me personally. 

. :)  This is due to you omitting important assumptions and also to partial misunderstanding of the tax rules.Before you gave your example, your opening question made sense and was actually insightful, thumbs up.

I know that a lot more clients would work with me over some other options if they fully understood the assumptions underwritten by some other lenders that might appear more attractive. 

Do not make any false assumptions about what other people should know.  

I always say this on the forums, but it always matters: the assumptions we make in initial analysis are always flawed- there's just no better way.

Would you ever consider buying with say a small negative after all costs (~$100) with the hope/assumption rates will come down and rents will go up?

Yes it may be a fair assumption to expect rents to continue rising but A buildings could see less demand as people are/feel poorer and dont want to commit to luxury living, and increasing unemployment could cause issues with collections for all classes of buildings.

The assumption in loan level bidding is they won’t sell the tape all together, but each loan to whomever they award it to.