have i done right? loft ..main beams.

[vw754]

Up in the loft i found the big beams... main beams...were not in a bad condition apart from these things 1 beam was split and had a bow in it .
2nd beam and 3rd beam had dry rot (about 2 inch across and 2-3 inch down) not much,anyway i treated it with cuprinol 5 star treatment.
have i done right?

The beam thats split,my joiner said he's going to get a timber beam of around 10 feet long and bolt it to the split beam is this the best way?

some ceiling joists and 2 beams also have some white spots moss like,are these something to worry about? what causes them ?