You can find out the name of a player on an opposing team by targeting them, right clicking and selecting "Examine". I'm not a huge fan of exposing opponent names more easily as it could quickly lead to bullying.

I agree that premades should only be matched with other premades in the interest of balance and fairness.

Regarding aimbots, if we're taking about CC then enemy players can be targeted via the player list. If we're taking about FL, it's possible an enemy had marked you and their teammates used the "target {marker}" feature to quickly target you. Alternatively you may have been "focus targeted" by one or more players so they could switch to you once you got in range. Without knowing more it's hard to say, but in my experience aimbots are not really a problem outside of things like samurai auto-LBing someone with that purple debuff.