Few questions; potential spoilers

So, being new to this style of game I’m a bit lost when it comes to training. I read that you can train with captain Bernard or whatever at the training ground. Does this continue after your basic training with him? Because he’s currently out on a mission, does he return to the training ground? Also as for archery. I’m brutal at it and would like to get better. How can I train that. Only by hunting/fighting or can I shoot arrows at the targets to train?
Thanks

Yes, you can train with him.

You can train anytime you want.

There are lots of trainers and they all have several levels of trading as you improve.