There are definitely more experienced archers who will hopefully chime in, but I'll give you some answers according to my experience. Incidentally, I started with a compound too, and although I still own one, I never shoot it anymore. Welcome to the Trad world!
I like bow quivers for a couple of reasons:
1. By adding some mass to the bow (longbow or recurve) they can help with stabilizing.
2. Lots of people feel (and I agree) that having the quiver mounted on the bow and peering through the bow and quiver at game can break up your outline to the animal. Effectively enhancing your overall camouflage.
3. The arrows are right there when you need them, easily accessible and within your field of view.
4. A lot of folks feel it's easier to stalk more quietly with a bow mounted quiver.
As for capacity, one old time archer answered this way, when I asked him about what capacity I should get. He said, "Well, I wouldn't want to go out with only three arrows, and seven's too many." I have stuck with 5 arrow bow quivers ever since.
My bow does not have inserts for quiver mounting, so I use the strap types. I would guess the insert types would work as well if not better.
As for specific quivers, I really like the Eagle Flight Archery quivers, but I also have a Selway Slide on Longbow quiver that I use 90+ % of the time. I shoot with it on all the time, so the balance of the bow is the same whether I am at the archery range or in the field.
I do, however, like to use a hip quiver or a back quiver for shooting matches at the range, while leaving my bow quiver on for the above stated reason. In a match, a hip or back quiver is so much easier to deal with when shooting a lot of arrows. I also think the arrow grabbers and foam on my bow quiver won't wear out as easily as they would if I was using the arrows out of the bow quiver for matches.