I just started climbing recently as well. I bought the book Toproping which I found to be really helpful. But, I think the best way (taking from other experiences as an athlete) to improve would be to go and talk to local climbers at your gym. The books help but I find that have advice from actual climbers is better. As far as videos are concerned, anything on youtube that you find interesting you should watch. Even if their form is bad its still a good video on what not to do. Someone recommended these videos for me and they helped. As far as the transition to outdoor is concerned I cannot help with that. I have only been seriously climbing for about a month or so and have no idea how to transition myself. Good luck, and thank you for your service I hope everything works out!