First-time owner of a Ragdoll Himalayan mix - any tips?

Hi everyone! I recently adopted a Ragdoll Himalayan mix about a month ago, and I just want to make sure I'm doing everything right.

He's around 3 months old, super clingy (follows me everywhere-even the bathroom ), and has bursts of zoomies but also loves to just chill and be carried. I've read that both Ragdolls and Himalayans are pretty laid-back and affectionate, but I'd love some real advice from people who've owned them.

A few things I'm curious about:

Grooming: His fur is getting longer-how often should I brush him to avoid matting?

Diet: Any recommendations for keeping his coat healthy and fluffy?

Behaviour: Is it normal that he's this attached? Like... zero personal space

• Health: Anything specific I should watch out for with this mix?

Also, if you have any general tips, routines, or things you wish you knew earlier, I'd really appreciate it!

Thanks in advance.