Yes you can set up Group Quick Keys for trunked systems. Scroll down the items in the left pane until you see [GRP] and the name of the imported group. After you click on that group name, the right pane allows you to edit settings for that group. The Group Quick Key box is just to the right of the Group Name.
After assigning Group Quick Keys, go back to the left pane and scroll up until you get to the system name. Click on that name and the right pane allows editing of the system settings. You'll see ten check boxes where you can Enable/Disable those Group Quick Keys you have assigned.
I'm a little confused about your "Can you assign group quick keys to individual talk groups" question. Every talkgroup is downloaded/programmed into a group. You can't have orphan talkgroups not assigned to a group.
Groups contain one or more talkgroups. While they are downloaded based on the RR database, with some creative editing, possible new group creation along with copying and pasting, you can shuffle/manipulate groups any way you wish.
The only caveat is that you have to respect the scanner's limitations, such as no more than 20 groups or no more than 10 Group Quick Keys. These limitations are scanner model dependent.
