[spoiler=why you shouldn't use 4E]
A normal troll would use game mechanics logic to argue against using 4E for anything other than hack and slash. And they would be correct. And I'm trying very hard not to link bomb you with examples of spells and skills.
But I'm going to use the meta-game argument. This is the srd for bard in <<
www.5esrd.com/classes/bard|5E dnd>>. This is the <<
www.d20pfsrd.com/occult-adventures/occult-classes/mesmerist|srd for pathfinder mesmerist class>>. This is the <<
paizo.com/pathfinderRPG/p...es/classes/mesmerist.html|official documentation for the mesmerist class>>. So in two steps I've got something that's mind control themed, I haven't had to buy something or pirate it.
This is the <<
dnd4.wikia.com/wiki/Cleric|cleric from 4E>>. You have a lot of dead links on that page. Now, if you try and come up with an SRD... you basically get screwed as a player and gm because of how the game was licensed.
It's a reality that you will probably need to roll house rules of some kind to support kinky d/s play and your particular flavor of mind control. 4E has, very little in the way of easy documentation and in game support for social play is ugly (again, lack of link bombing going on right now).
[/spoiler]
That rant out of the way, some good advice for the other stuff you asked. Roll20.net supports good dice rolling and maps. Mythweavers supports good character sheets (thanks to someguy231 for asking if he could use them). Hypnopics-collective.net has a dedicated rp forum, it isn't so good on dice or maps. They have a lot of freeform rp's.
I can vouch for Pathfinder as having good enough rules. I would not roll something more complicated like Shadowrun (and I'm a terrible fucking fanboy for Shadowrun) unless you know you have a good team of rp players. I haven't used Savage Worlds for kink yet. When playing irl, cc took no more than half an hour on a sheet of notebook paper. But there's also so many free systems out there, when I checked, it might be worth having a look at those (I've heard mixed things about Fate).