I would remove each screw, sikaflex in the hole and and put the screw back in. There should be enough sikaflex so that some oozes out all around the screw – as the screw beds down.
The screw will probably go in quite easily – and be careful not to apply excessive force and the grp is fragile.
If the grp is very fragile you may want to use epoxy filler first – and try to beef up the area that the screw goes into. In which case it will have to be re-drilled once set.
Repairing the bailers is fairly easy – but you may find it difficult to remove the old bailer without damaging it beyond reuse.
Clear out as much of the old filler between the inner and out hulls as possible and then apply new.
hope that helps