I understand the basic principles of subject-to, lease options and seller financing and I was curious if there's harm in asking the owner (based on their selling situation) if they'll consider a subject-to, lease option etc.?

You could also do a subject to; often you may not need to put any money down to control the deal.There are a lot of great post here on BP and highly recommend you understand all of these options further.

Your losses on the rental from schedule E will go to offset ordinary income (subject to certain ceilings based on AGI).

I would get it under contract with $3K net to him subject to you negotiating an acceptable number to the bank and any other lien holders.

Your explanation is a little confusing but I think your referring to a Subject To transaction.

A great book to read on this subject is, "the abc's of real estate investing" by Ken McElroy.This process has helped me identify a bad deal much quicker so I can move onto finding the very rare Great Deals!

Needless to say, significantly lower than what my payment will be.I'm considering offering to do a subject to purchase agreement to allow more cash flow and have a greater chance to put together the cash I'll need in 5 years.

BP has even written a book on the subject specifically that you might think about picking up.

All of these sales are subject to the sellers approval.  

I look forward to speaking with you more on this subject in the very near future.