Well, this is my first post on this forum, as I just found it, and have only been poly in the past year. You're asking about rules... "I just wondered if any of you have similar rules, but have amended them when they were put into practice? Or have any opinions on the rules we outlined? I would like to learn :-)..."
Yes we have rules... the way it was when we started, was I was only allowed to kiss other women, nothing else. As we grew more comfortable with everything, it grew to sex with women, as long as it was in our house and protected, then it was sex with women outside of the house as long as it was stable, and my husband has recently suggested that I find a stable girlfriend.
I have one ex girlfriend now, and as of last night, I have a new girlfriend. We have rules within our poly... my husband requires a few nights at home a week, and for me to not leave him for my girlfriend (which I never would.) My girlfriend has a young daughter who is easily confused, and is in the military, so we do not show affection in public. Aside from that, everything flows by how we all feel. My husband is straight, so has no boyfriends, and he does not get involved with my girlfriend either (as she is a lesbian). I'm sure that throughout our lives, mine and my husband's rules will change, and we may end up monogamous at some point, but for now we are enjoying our poly lifestyle.