just curious.

Yes, they have a cybernetic implant cap of 6 instead of their Brawn rating.

For a droid, cybernetics are the in-game mechanism for "upgrading" their chassis. Rather than create another system in the basic books, they have just said "use the same rules". The up side of that is that it keeps the droids from upgrading to ridiculous stats with just cash. The down side is it seem hideously expensive for what are in some cases basic upgrades.

Yes they can and boy did our droid take advantage of that... Legs, arms, brain... So many "free" ability upgrades... We got our hands on a bucket load of credits and before we managed to get rid of them he spent some. (but remember kids, no force sensitive droids).

The down side is it seem hideously expensive for what are in some cases basic upgrades.

For this reason, I composed myself a document that describes how the different upgrades work for droids, as the cybernetics are written with meatbags in mind. I also adjusted some of the prices for items that would make sense (such as the droid equivalent of the simple prosthetic organs/limbs being cheaper and more common than the cybernetics).

Can a cyborg not a droid have so much cyber ware they are almost not human anymore but also be force sensitive? Will it affect their use of the force

I would hazard a guess and say no.

We have nothing in RAW to guide us on a cyborg PC. They may choose to ignore that little bit, who knows.

Edit: Although a Gank can us the Force and has a huge capacity for Cybernetics, so who knows.

So best bet is to follow ganks limitation as closest to a cyborg. How much cyber ware does Vader have? Or it more just a suit and cyber limbs?

So best bet is to follow ganks limitation as closest to a cyborg. How much cyber ware does Vader have? Or it more just a suit and cyber limbs?

Lots, but not as much as Grievous. They are really just major NPC villains so have as much as the GM needs.