advice on preparing plasterboard sfter stripping wallpaper

Better of using lining paper

 

As Windsor says. Either that or have it all skimmed - obviously more costly.

If you try and patch the rough bits using very thin skims of filler, you'll likely be giving yourself a long-term task; when you sand the filler down to get it smooth and level, you will almost certainly break through in parts to the rough 'board again, and the applied paint will show that up. So it'll be patch, patch, patch again...

 

As above, lining paper.

Don't use a thin paper though, use a minimum 1700 grade but preferably a 2000, this will require a certain skill to hang due to it's weight and thickness.

Now this may or may not confuse you, hang it length ways around the room, side to side as opposed top to bottom.

 

Yes, there are less joints, normally only 3, but it's mainly to do with light coming in through a window, it tends to catch the vertical joints more so than horizontal ones.