I use a Sidewinder X3 at 2000DPI with no mouse acceleration (default 6/11 in Windows settings with Enhance Pointer Precision off and the
MarkC acceleration fix applied, which I don't think really does anything but I do it anyways because I always have). I'd have to check what my in-game scroll speed is, but I try to set it to the highest speed possible for myself while still being able to keep control. Scroll speed is really personal preference though, as you practice more you'll find yourself using edge panning less and less, and you'll get a feel for whether your scroll speed is too fast or too slow, and you can adjust things to your liking.
I'd say gridkeys are more efficient simply because it requires less hand movement since all of your hotkeys are on one section of the keyboard. It also makes switching between different factions a lot easier because you only have to remember one set of hotkeys. I use gridkeys in pretty much every single game I play these days because I find the muscle memory translates nicely between titles.
Tactical map is one of the most useful control elements in CoH. It's unfortunate that CoH2's tactical map is so crowded with extra information, but it's still an invaluable tool. I usually use it to position units before engagements and set up capping after fights, while reverting back to the regular minimap during combat because it gives you the overview of the tactical map but with better precision and slightly faster movement around the map.
Control groups are great, but they're not nearly as vital in CoH as they are in other games. When I started I put every single unit on the field into a control group because it made keeping track of things easier for me, but as I got quicker and more comfortable I cut back to only putting vital units in control groups, things like vehicles, snipers, AT guns, and artillery. Something I like to do is rebind my 0 control group to the tilde (~) key, which gives me an extra easily accessible control group right beside the cluster of keys that are used for hotkeys. My usual control group setup is:
~: Scouting vehicle/secondary vehicle group
1: Primary vehicle group
2: AT guns
3: Sniper
4: Second sniper/artillery
5: Artillery if I have a second sniper, or mortar if I have artillery
6: Mortar if all other groups are in use (2 snipers and artillery on the field)