Likely the family who adopted him before handled him wrong causing him to act out, or as they saw it “aggressive”. Many rabbits absolutely hate being handled. They are not cuddle monsters like media portrays them to be, most of the time. Most buns are ok with pets at any time, but will only allow snuggles, cuddles, and carrying on their terms. And being that his last home may have handled him wrong, then was never handled properly afterwards, it is very possible he will only learn to tolerate it if need be (to vets, and such)
To get him into the carrier, you can bribe him into it. I have to do this with one of my buns. Just a bit of greens, pellets, or a treat set all the way to the back and that usually does the trick
For nail clippings, it might be best to have the vet do it if you are nervous. If you feel you can do it yourself, i see the Bunny Burrito recommended a lot
1. He may not be too old to be retrained, but it will definitely take some love and patience. You will only be able to move at his speed or you have a high risk of him hating it again
2. I do with my Bombur. Well, i lift him when i have to, and he is ok being held on very rare occasions. But on a weekly basis, he is not handled at all unlessyou count pets. We bribe him around with treats
3. Only if the vet is unprofessional. My Bombur has cut up our vets hand before and she didnt complain
She would work with him sitting on his mat on the table and only lifted him when she needed to
4. Every rabbit learns differently. However, i dont see how clicker training would work with being held…
5. As every rabbit is different, for me specifically, theres nothing thats trained my Bombur to “like” being held. With treats he is ok with it and wont fight for a few minutes, but when he gets mad enough he will start trying to box again
6. We use greens and pellets as our go to “treats”
7. Move at his speed but realize that he may be a bun that will always refuse to be handled