So I bought a used Fuji Q4 for $200 with gun and hose, it works well, but I would like to know what kind of spray gun this is and if its possible to get different needles and air caps for it. If there are any rebuild kits available.

It looks kind of like a sicmo, but close to a graco??

Any and all info would be greatly appreciated

That appears to be a SICMO built gun which was probably built for Fuji. I would think the SICMO air caps and nozzles would work however that gun is "shorter" front to back so that means the needles would have to be shorter as well, so you'll need to go to Fuji. I'm sure SICMO needles could be cut and threaded as needed but I'd just try and get the right parts.

Okay, did a little knocking around the net and found....
http://www.hvlpsales.com/accessories.html
Says, that dealer has been a Fuji dealer since 2002 so they should have "some" parts for that older style gun. Fuji appears to be phasing out some of these older parts so you might want to do some searching around on ebay, craiglist, etc., if you have trouble finding new.

It came with a 1.4 tip, is this tip ok to spray metallic basecoat and a medium solid 2k clear with or should I get a 1.0. Also which tip should I get for primer, and lastly can this be converted to a gravity fed with something like this. http://www.brettwood.com/inc/sdetail/3017

You should at least try the 1.4 you have. The turbine itself has a lot to do with what tip size you go with and of course, the material viscosity. As for polyester (Slick Sand) heavy bodied primers get the biggest tip you can, however I'll be honest with you I am not a big fan of using this type of gun for those heavy materials. I'd rather just run a cheap gun with a 1.8 to 2.2 tip to hose them on. I mean, we're going to sanding most of it off anyway.... If you are spraying more like a poly 2k or epoxy primer the tip you have now might be okay.
As to that cup conversion there is nothing particularly wrong with it especially since you've already got the gun. It just has a little harder time pushing thick materials out of that cup with smaller turbine set-ups. If you are running a 3 or better yet a 4 stage turbine you'll have more pressure in that cup. Hope that helps.