[Caio]

I was going to say there are two options.

I agree with Hachiban in that the balls will be delivered from the hole. In proportion, it looks like you have a two inch roller or maybe a little more depending on desired compression.

As for mounting, I would say you're more likely to mount it on the bottom since that angel creates too much of an arc (imo) but you could also be mounting on the top.

As for a gathering system, that I don't know