#1

(you can skip to about 1 min to see what im talking about)
can someone please help me? I want to learn to develop strumming like this but i can only match it like half way half of the time, and even then ill try to transition back down to 1/8 notes and it just sounds shitty whereas when he does it it sounds so clean. The only tutorials i ever find on Reggae are just 1/8th notes with a down chuck on the off beat, and maybe muted strings or root note played on the beat if that even but as you can see this guy and others like him seem have taken it to another level
#2
Not quite sure what you mean about strumming technique, there are quite a few dead strums thrown in if that's what you're hearing. That's just touching the strings, not fully fretting them.

Also, practice that much that you don't even have time to wash your hair!