Jewelry Pearl Necklace Loose Beads

1) Is plasterboard joining tape for use with square edge plasterboard and tapered plasterboard or just tapered edge?

2) Is it to stop cracks appearing between sheets of plasterboard?

3) Do I have to plaster over this tape or use some type of filler? If so, what?

4) Do I use beading for corners or can I use tape? Does this need to be plastered over or can I use some time of filler?

5) I've also been told that the two sheets of plasterboard would meet to make a corner and the beading would go on top of this to make it strong and perfectly straight. However, this would obviously need to be plastered or filled, put wouldn't that make the corner slope out cause of the plaster that would need to be added to cover the beading??? Surely the plasterboard wouldn't be flat anymore cause of the plaster on the corner edges?

Any help appreciated!

Thanks