different feeds

Seriously...what's with the use of "like"?!  Have they stopped teaching grammar in schools?

Anyway, this is something you should easily be able to look up on your own.  The older autococker models used to have the balls feed in at an angle, usually called a right feed.  I'm not positive but I don't think that anything made after 2k or 2k1 is a right feed; they're all vertical feeds now.  You'll also see that some other manufacturers, like AGD/Automag and Kingmann/Spyder, used to use a "power feed".  It was a feed off of the left, that came down to a breech on the right side of the chamber.  What made it a 'power' feed?  I have no idea. 

I think the original reason for having the hopper feed from an angle was simply that people naturally sight their shots from the top of the gun and down the barrel...so they were moving the feed out of the way.  Obviously they figured out that it makes the gun wider than necessary and people can easily sight from the left or right of a vertical feed.

Making it a vertical feed?  Well, unless you have a machine shop, you won't be making anything...you purchase it that way.  It's either a vertical feed or it isn't.

Yes, you can feed paint horizontally. It's called the Cyclone Feed System, patented in 1993 with the Factory F/A and actually didn't see widespread (read:any) use until the A-5 hit the market with the Cyclone.