The most easily correctable things I see guys do is

1) hips are too close to your heels

2) doing negatives on the way down.

That will give you a few more, but overall I would recommend just varying your training if you can. When you are doing ab exercises look up some ab exercises you have never done before and just do a 10 min session of whatever that exercise is and you will see a difference.

Yes, first thing is work on form so make sure when you are in the hang position that your scapulas are set and flexed, your grip should be high up on the bar so you are not just using your fingers. First work on your volume, then refine your form. If you can’t do more than 5 pull-ups then I would also recommend using a resistance band by wrapping it around the bar and placing your foot in the band

There are lots of countries I have been to where French is a secondary language, but I don't think the next couple wars will always be in the middle east so I would recommend learning the language that most interests you.

Physically it will absolutely put you ahead of the game, and it exposes you to the techniques and standards that you will experience in the water. If you finish the program to a "T" then you will not have to worry about the physical portion just focus on the team and the mental portion at selection.

It is difficult and sometimes frustrating, however you can practice on the land laying on your back, then move into the water and hold the wall, then move off the wall and use some type of floaty to hold you up, then ditch the floaty. Also if this doesn’t work and you cannot get it down, you can grind through using a giant stride/flutter kick variation.

One thing that helped me was alternating with hand paddles and fins. It really helps you feel what movements will help you propel yourself in the water. Also a big thing people miss is working on reducing your time on the wall during turns.

That is definitely a tough situation, one factor to consider is that you can be a PJ then a pilot but not the other way around. Overall, I would say to do what you are most interested in, watch videos and read books about them. Then when you decide, go all in.

If you have inhaled as deeply as you can and you are still not floating then you may just be a sinker. It's okay to be a sinker, but you just have to be comfortable with kicking to the surface a little bit.

Find someone who is good at swimming and ask them to teach you, or hire a coach. Swimming is all about technique. Total immersion is a great resource.

You can’t really replicate pool workouts, but I would use a row machine or the versa climber/Jacobs ladder. Just something that is low impact and uses upper and lower body.

It's all about flexibility and coordination. Look up some hip flexor and leg stretches and do them religiously. Then watch some YouTube videos on the eggbeater technique and practice on dry land, just laying on your back , then practice in the water while holding the wall… then progress to timed sets in the water.

I would do some interval work, like 400-800m and do one day a week where you run 6-8 mi.