Solid in the front will give you less of a turning radius since both wheels are turning at the same time. Solid in the rear, you have to squeeze instead of punch the throttle since the rear will get all loose on you.
As far as braking, yes you need to break but with different degrees of application. With a locked or open diff in the front, you have full breaking, and that lets you outbreak in the turns/corners. Hard in, late breaking and coast through the turns with power as you exit. With a oneway, you ease into the turn with onpower steering to power through the turns. Setup your car for the turn, blip to correct and keep steady and power at the apex into the exit.
Sounds like a lot of things happening at once but you get the hang of it and it becomes second nature. It wil make you smoother which in turn will drop your laptimes. Running with a pack will distract you but as I said, the more you do it (race and even compete with others in a lot), the more it becomes second nature.