although I am all in for open relationships (or at least non monogamious), I would not advice you to be in a open relationship... especially when you are not living together... I think that it is very good of you to have thought of "rules" and possible issues, which are nessisary in an open relationship... it is healthy to consider... but I would not go there, under these circomstances...
just.. no...
Feelings are powerful things - they override our minds and our bodies, as if trying to control us. We are but mere vessels for them to carry out their will.
Your Friend - Bjarke T.