it depends how much you play, but 99 slayer will take awhile. Theres really no guide you need, just go to the highest slayer master you can, get a task and repeat.
A cannon will help slayer tasks go by faster, so thats a weapon you get get. Also, a lot of slayer monsters are weak to stab, so get a good stab weapon.
Theres also no recommended stats or quests, becuase you level your stats by doing the tasks. Just get a task, do it, and repeat.