Welcome aboard, depthtok33l. Always fun to have a new guy to push around, err, I mean, share our vast wealth of knowledge, and provide guidance.
Your first question. I don't use Steam, so I can't help you on that end. On the loading screen of the game, look at the lower right hand corner. That will give you the version you're running. When you can, go ahead and get the U-boat expansion. The latest mods are written for it. It also fixes a lot of problems. You don't need to upgrade incrementally, the U-boat add-on upgrades it to version 1.5 and includes all the up-dates.
Your second question. Personally, I still use auto-targeting. I learned how to do manual and can do a decent job with it, even sonar and radar only attacks. I just simply don't like it. There are some advantages to using manual. It takes a lot of practice. Find the tutorial that works for you and do your best.