So I have this bush on a trellis. It was like that when I bought it.

It's growing fast in just the few months it's been here. As you can see I have a bunch of longer branches coming forward and backward off the trellis. I know i can leave the short ones alone that are just foliage, but for these long ones I have some questions.

1) For these do I cut the super forward growing ones? Or if I trellis, can they be trained to grow upwards?

2) I need to remove the trellis behind it and put in a bigger trellis. When I do this, the stuff that is attach to the trellis now, do I need to reattach it all over again? Or it's it's growing vertically nicely (and it's pretty sturdy in that vertical position) can I just leave those branches alone and not reattach them ? And instead just attach any branches that are not growing nicely upwards?

3) Lastly, any good books on this you recommend?

Thanks so much!