I think one of the big lessons here is that one should carefully consider the parameters of the planned dive, and what critical functions you might need to back up. I would say that, on any dive where the possibility exists that you might incur a deco obligation, that knowing one's depth and time is a critical function. Many technical divers carry redundant gauges; I don't, but I carry buddies . . . if I were ever to contemplate a dive such as the one you did, I WOULD take a backup gauge. I would also take a redundant gas supply, as I regard enough gas to complete the dive as a critical function.
I think this dive was poorly planned and ill advised, and I think you were lucky that you weren't bent worse than you were.
With respect to the subsequent renal failure and hypotension, your analysis is almost certainly correct in part -- being on Flomax and Lisinopril is going to complicate any situation where your blood pressure is likely to be low. But, to my knowledge, there is not usually anything about DCS that produces hypotension -- and renal failure usually produces the opposite. With a baseline creatinine of 1.2, you have some degree of renal dysfunction at baseline; although that may be the upper limit of normal, it is rarely seen in normal patients. Whatever the etiology of the hypotension, it certainly aggravated the renal problem, and it is a very nice outcome that your creatinine normalized. Did you get any IV fluids during your original hospital visit for the DCS?
I think, if I were you, I'd be extremely careful about entering into any situation that would put my renal function at risk again. Staying well hydrated at all times AND avoiding risky diving would both be good plans.