That's a good question. We were a bit on and off as an actual couple for about three years, but the master/pet part wasn't for the entirely, only most of it.
Oh man. Lots to choose from. I love restrictive tortures and she reacted really well to them, so there were some really intense ones we did that revolved around limiting her field of movement for prolonged periods of time. At her request, we did a rape fantasy once, which was decidedly intense.
From how things ended, and from what I've seen with similar relationships, there's a degree to which dynamics like this can be more vulnerable than 'conventional' relationships. Ours going south was ultimately a lack of communication: after a while, we came to want entirely different things from the relationship, but both made the mistake of not really voicing it until after there was some serious damage done. Things ended civilly, but ended nonetheless.
At a superficial level, some of the stuff we did taught me that I have a serious Neko fetish. On a more personal level, it's taught me that good relationships are less of pursuits and more of co-op adventures. I've seen a lot of couples, especially ones founded around dom/sub go south really quickly, but stay miserable together out of obligation and expectation. There's a certain amount of give-and-take you have to do when making things work on a dom/sub level, but if a relationship is draining you more than nurturing you, it's time to stop.
Wow, this question is going on a while. I'll tackle the next part in a separate bulletpoint.
Being constantly forced to stay on top of innovation for being a dom is a valuable experience. A lot of people just sort of go into it with the whole 'Fifty Shades' aspect where they focus entirely on the sex and basically just start hammering on physical restrictions to a scene. In reality, god dom-ing isn't about just forcing someone to do something; it's about coaxing out surrender. Adding elements where the sub is encouraged (or forced) to react or adjust keeps things interesting and makes for more intense sessions.
Basically anything with caramel.
As I said, dominance is about surrender on the sub's part. To that end, things are generally at their best when you're keeping the ball in their court. That being said, if you're focusing on harsh dominance 24/7, you're going to trigger a crash really quickly. Instead, it's important to keep a degree of nurture present outside (and inside, in case of afterplay) the bedroom.
Probably. I've randomly been so busy I barely have time to talk to other people, let alone do kinky things with them.