Couple of things. Ron's Rocks as several have said is not a site that is dived very often, mainly because the seas and currents at the west end of the island can be pretty screwy and change quickly with little notice. So things have to be pretty calm before they will even attempt it. With a newish DM, who may not have dived the site very often, it isn't surprising they may have gotten turned a bit if the current kicked up from an unexpected direction.
Regarding getting on and off the boat, if you want more freedom, get in the water first and leave the area before the DM drops in. I will typically be ready to go with mask around my neck and fins in hand by the time the brief is finished so I can drop into the middle seat as soon as they say the pool is open. You can follow their suggested path from the briefing if you want to do the swimthroughs or you can go do your own thing. My experience has been that if you are staying with the group and following the DMs, you will get more attention from them than if you head off and do your own thing.
As far as them grabbing you underwater, if they took your path as "ignoring" their instruction to come back above the max depth, I can see them being upset, but on the other hand, my personal experience is to never have an argument under water. They should have addressed it with you back on the boat and grabbing underwater should be a last resort for divers in serious danger.
They are generally very relaxed about most of the guidelines, but the max depths for the 2nd and 3rd dives in particular are something they are somewhat serious about. If the max is supposed to be 60 and you drift down to 65 for a minute or two, they are unlikely to say anything, but if the max is 50 and you are at 75, expect to get their attention. Once you are on their radar like that, you can expect more attention for the next few dives. Having a quiet discussion on the dock to explain what you were doing is a good way to defuse some of that.
What one of the posters was talking about regarding the "middle seat" being quicker is that there are two bench seats at the back corners and then there is the small step down on the deck between the two ladders. That small step in the middle is the "middle seat" he was talking about. Generally, the older and/or less fit divers will take the bench seats at the corner and most will shy away from the middle seat entry because it can take a little more effort to stand up. I have seen a few times where divers that were known to the DMs (usually local residents or former employees back to visit) were allowed to do a stride or back roll off the step at the side, but I have never seen them allow a typical guest to do that. If you are looking to do something different than what they have planned for entry into the water, my advice is just to talk it over with them ahead of time so you don't catch them by surprise. Most of them are pretty accommodating if they understand what and why you are trying to do differently.