You need some digital scales to weigh him, you need to feed him 10-15% of his body weight, rats are better for balls but it can be hard to get them on to rats, Also this site is very helpful you seem to have done your research though so your off to a good start.. when it comes to handle it they don't exactly like being handled but just tolerate maybe just start around 5minutes a day and gradually build up that time.
You will not need to feed in a different container, cage aggression is a myth and feeding them in different containers could stress them and can make them more likely to bite you, feeding every 5 days is a good schedule when it comes to younger ball pythons, you sound like you have everything covered, being on this website your knowledge will grow quite a lot.
But yes, i would advise on buying your BP some digital scales and feeding 10-15% of body weight e.g:
Snakes body weight (135g) x 0.15 = (20.25g) rodent prey weight
Hope this helps, and welcome!
Ye it is normal for them to climb, 70% is fine as long as your not seeing condensation etc... a way to get this is down is putting an osculating fan in the room