my question is in regard to grounding...i am confused on whether to use the seperate equipment grounding bus bar or
remove the neutral cross bar and ground on one side there

i know that a subpanel needs to have the neutral and grounds seperate, but wouldn't they be seperate anyway if i just grounded to the seperate equipment ground?...if so...would i have to remove the neutral cross bar if i'm not putting ground wires on it?

thanks..have run an insulated ground back to the main and have driven a ground rod for the sub (in seperate building)

last question is on whether to where to use the bonding screw that came with the box

This panel can be configured either of two ways to accomplish this. You can either remove the bonding screw, leave the cross tie in and use the two bars along side of the breakers are your neutrals while using the one screwed to the case side for ground

-OR-

Remove the cross tie, install the bonding screw, and use the neutral on one of the bars and ground on the other.

Frankly, I think the first option is cleaner. I like having the neutrals landed close to where the hots are.

Sounds like a good reason to add a new ground bar rather than bothering to disconnect the two provided bars from each other.

I like having neutral bars on each side.
It allows landing the neutral for each branch circuit near the breaker for the hot.
If space is available I land the grounds nearby in main panels also.

so my panel has an independent ground bar allready...
(this box is sold as a subpanel, so it looks like GE separated the ground bus from the neutral)..ground bar is off to the side

so i will not remove the neutral tie bar in this case since
the neutral bar and ground bar are allready seperated
(as i understands this)

This panel as I said originally can be configured in a number of ways. For your situation leave the neutral bars tied and as the neutral bars. Put the grounds on the other.

The other application for this panel is an isolated ground system. In that case you can split the neutral bars and use one as an isolated ground. You don't much see this done outside of certain sensitive electronic and medical applications, you need specialized receptacles, etc... to maintain the isolation.

I see a green boding screw in a seperate plastic package
and no ground screw on/in the neutral buss

so i guess i simply do not use this screw

i plan to put a surge protector in the main panel, so hopefully I won't have a problem with electronics