Hi
Yes as as said by Alexandar you will need to customize if you want to only update certain items, as per his post you can look at the way it updates, you could also create a tick on the items that are modified and use this to only populate the correct items onto the standard cost worksheet, you could also have the system process everything then delete all the items except the Finished goods you actually want to update before you press the implement button
My recommendation though is to see if you could rather update all when you run these updates, i have found in the past that items can end up only partially updated or missed entirely in the update when trying to only update certain items
On the SKU, if you are updating the item but not the SKU you are in effect not updating the items cost as the cost of the SKU is used when the system looks for a cost, not sure why you would want to leave that out?
Hope this all makes sense?