DON'T buy recasts, only the original manufacturer will re-issue kits(which is rare).
No japanese manufacturer, sculptor, etc name given = pirate copy.
Working with resin compared to vinyl.
The big difference here is in parts cleanup and assembly.
I recommend 2-part epoxy glue(5~10 min. setting time) for assembling resin kits and you should reinforce all joints by inserting metal pins.
Your primer. putty, etc should work ok for resin and after that there is no difference to the painting process nor any requirements as you paint on top of the primer.
Quality of recasts.
Depends on who makes them, but in general they are of way inferior quality and use poorer/cheaper resin.
Recasters will also often semi-preassemble kits in order to cut down on the number of parts that they need to cast.
Said that even with legit kits the quality can vary betwee makers with the top-of-line kits you open the box, throw in some glue and paints, close the box, shake it and an assembled kit falls out.