You dont have to use a roller but if you have one then bonus. Even a hand roller will do the job. With Ps just use a straight edge with cloth over to push out any air.
I'm not really fussed what I used to be honest, if I have a tub of 2000s and f44 on the van then I'll always use the 2000s for sheet but still use 44, just depends. I done 120m2 of sheet at a nursing home couple months ago and used 44, went down lovely. Obviously rolled it due to the length of the drops. I always have a tub of 2000s laying around and use 44 on some planking jobs aswell. 2000s I mostly lay in wet, same with 44 but do sometimes let it go off.