I did that myself in my old house and swore never again. (did the whole bedroom)
It takes ages and if you put to much plaster sanding it back down is a mission not to mention if not done properly it shows through after its painted. The dust and messy it creates not worth it. Defiantly need skill for that I would highly recommend getting that done professionally.
Painting that can be done by anyone, yes even you I'm sure.
(my wife and I tag team in painting. You never know the DIY skills they have till you get them to do it haha).
The main thing is prep work. I spend more time to prep the area then to actually do the work as if prepped properly you can do the work much faster.