some questions about Champions Mastery system

there's alot of titles, like for tanks, and Assassins, support, mages, Fighters and Marksman

Q 1: say i'm playing Nautilus, and say i'm playing him as support constantly, is there any way to earn the titles of a support/Fighter instead of Tank? doesn't my playstyle effect this?

Q2: can you overearn points if you hit level 5 mastery with a champion? because i have achieved level 5 on two champions, only to find one of them were on 22.3 k points and is max Mastery, while the other is 39.7 k Mastery

and i'm not sure if i have been over earning in the other, as they're enlisted on different roles, one's a Tank and the other is a Fighter (which is funny because i play him like a Mage)

Q3: IF and we're implying you can overearn point, will this somehow lets you level up immdediatly when they release further levels in champions mastery?

that is all, thanks!