1. Not sure on #1. For USNA and the other SAs they give a requirement for Appointment Acceptance Date. Its usually in April to May timeframe. Not sure on USMMA. If it really is that long of time, then sit on it and see what offers come. It is always a draw for someone to be wanted, but wait until all the offers come and then really make a decision.
2. Once he commisisons he will honestly have the same shot at everything in his career path of anyone else, regardless of career path. There are plenty of examples of officers succeeding at all ranks from every commissioning source possible.
3. It is a mixed bag on this. Depends on the waiver also. Color blind varies between places like USNA and USMA. I think its a good sign, but it really varies.
4. If he is deemed a qualified candidate he will be submitted for a waiver. With the MOC slates being entered now and due at the latest 1/31, if he has a Nom and is deemed 3Q, the chances are good he would be evaluated for a waiver. What did his BGO say on his competitiveness?
5. I would say the experiences are different and almost hard to compare. Also what is right for one, is not right for another. What place feels the best and set him up to succeed? Also, I think it depends. ROTC at an SMC is probably a different experience then one at State U. What environment is best for him?
Couple of comments, and they are just purely my opinions. I hope someone from USMMA can chime in and give theirs. Take a look at the USMMA threads and really understand the mission of the school. USNA's goal is to commissions Naval Officers, while USMMA is to make Merchant Mariners. The training and education is all geared towards making a qualified and prepared professional mariner. I think its also important to research and understand the rates of commission from USMMA for the Navy. How many get pilot as their first pick? Subs? SWO? Can he participate in summer training? What is your son's goal and how do these numbers match up. Have you visited USMMA to see and feel if its the right fit? Regardless of his desired path to upon commissioning, hopefully someone from USMMA can correct me if I am wrong, to graduate he has to pass his licensing exam and will go to see for his trimesters regardless of what he wants to commission.
The Nuke Enlisted path is an interesting one. If you look at USNA stats, the Nuke program, provides alot of prior enlisted. In fact they will pull highly qualified kids from the pipeline who have impressive resumes, have done well in Nuke school and demonstrate the maturity and leadership skills and send them to USNA. I think out of the 4 priors I had in my company 2 of the 4 were "priors" but had never seen the fleet as they were pulled from this program. But, as I caution anyone going this path of enlisted, be prepared to serve your entire enlistment if you sign on the dotted line. Yes, he can always apply later, but CO's endorsement is required. A CO could simply say, I want to see him perform for 3,6, or 12 months prior to endorsing.
Good luck!