What monitors are used in the LCS?

Also can players use their own KB and Mouse?

From what i have seen, yes. That, or team-sponsored stuff. Forcing standardized peripherals would be a disaster.

As far as the monitors, i cant find any info. Probably just generic high-quality 1440p 144hz panels, unless someone is doing a sponsorship for their overpriced gamer-crap, like alienware or asus.

As far as i am concerned, the game is better on a 21:9 (wider field of view in most lanes), but those only go up to 75 or 100Hz in most cases.