will a plasterboard wall hold a 8.7kg telly on a bracket?
Only if it is screwed into framing, not just the plasterboard.
Yes, so a plasterboard wall simply hold a 8.7 kg.
Yes as the weight is in a downward direction make sure you use plasterboard fixings work carefully and don't make the holes too big if you are using plasterboard plugs then a good test is to hang on the bracket as a test before fixing the tv. if you are not sure then fix a 9mm plywood or MDF panel the same size as your bracket then you can use additional fixings good luck
As-long as you tie the bracket into the wall joists you'll be fine
