"rent back" till death

[Orlo Flock]

I've recently come across a seller (a 91yo lady) who wants to sell her house with seller financing, interest only, with at least a 10 year balloon here in Oregon with approximately  $10k down.  All fine and dandy.  The clincher: She wants to "rent back" the house (with the rent amount being equal to the financing cost) until she passes on. At that point the 10 year clock would start ticking and the payments would go to her heirs.   I'm okay with it but:

1) is there a better way ,tenants in common maybe, that have us split taxes, insurance, etc., till she passes.  In case she finds the fountain of youth of a sudden.

2) is that legal?

3) is it possible for her to not be my tenant per se.  (I.E. a clause that I don't pay for any repairs or maintenance under $400 or better yet relieves  me in  total from being her landlord)

4) any other consideration I should take?

I don't  want an option: she could stop paying insurance and  taxes or get liens, etc. and I'd possibly lose the asset and my option $.

Thank you for your go headedness!

    -O