Assuming you're using the default setup, find the spring stiffness/rate setting (it will be a 3-digit number with the units "N/mm"). Increase front and rear by 2 clicks. For example if its at 320 N/mm, +1 "click" may be 340, +2 clicks may be 360.
I would increase for front and rear, the same "number of clicks".
I don't understand - what negatives?
I'd follow Scott Mansell's guide. You need to have patience through Luffield for a good exit.
Don't follow AI lines. They're often not the best line for the player car to follow. Simple physics model on AI cars allows them to do things you can't. That said - fast guys can smash AI almost everywhere at the max difficulty so it's not impossible.
There are only 2 "styles" - correct and incorrect.
Most of us fall in the latter
Ps - 6 clutches on the diff is the middle setting I guess. I'm not confident enough to explain or advise on diff settings.