1) No because he has more than adequate savings in order to support himself. Though you'll most likely lose your jobseekers due to his savings once he moves in with you and you'll need to report the changes in circumstance.
As a British Citizen (under visa rules) you can receive any benefits that you are entitled to (meet the requriements for). However if your family will be solely dependent on benefits it may be difficult to meet the maintenance requirement. But, this is where his savings come it to show that you won't need to claim ADDITIONAL benefits in order to support him.
2) It depends on when he applies if you're working. If you are working then you need to provide your most recent 3 months worth of pay stubs and if you've just started a job then any paystubs that you've received PLUS your job contract. If you're not working at all when he applies then you need to provide the appropriate documentation of whatever benefits you're receiving at that time. If you have documentation from your employer about getting laid off and then your reinstatement at a later date you should definitely provide that as well.
Edited to Add: More information on the
Maintenance Requirements (and Accommodation Requirements) can be found HERE I suggest that you have a good read over it and if you have any questions please shout
