1. Yes, well at least a AAA flip seat bracket. I started out with the NRS seat bar and low-back and liked it but I ended up switching for two reasons. First, I wanted more storage space so I decided on a flip-seat which now sits on top of my cooler. Second, I wanted to sit a little higher than my passengers sitting on top of the dry box in the bow. This has helped my line of sight over their heads instead of having to stand up or look around passengers. Having your cooler under the flip seat is really nice i.e. no unnecessary opening of the cooler and your beer stays well guarded while you are rowing
I just use a soft-sided NRS cooler for the day with beer and snacks.
2. When I bought the flip seat bracket from AAA I also bought oar towers that fit the NRS diameter pipe that are tightened with hex screws. These have worked great. I did have to end up putting 1' oar extensions on my 10' Cataract oars so I had a comfortable angle on the oars which you may need to do.
There is obviously pros and cons to every which way you set up your captain seat. Personally the pros of sitting a little higher to get a better vantage point and the added bonus of keeping the cooler from being opened all day long by passengers if the cooler was located elsewhere far out weighs the potential con(s) of not having as low as a center of gravity, etc.
If you can row on other peoples boats that have different set ups and figure out what you are most comfortable with before committing that would be ideal. My experience over the years with this wicked addictive hobby/sport is that any change you make is not cheap so might as well take each setup for a test drive before deciding what you like cause it really is all about personal preference and what you are comfortable with.