My advice always is to start very simple and master your timing and master the most simple beats that you can, and you just keep elevating from that. Trying to go right into playing fast is not necessarily the best way to go about it, because if you don't have your foundation locked in, it's hard to progress.
I don't use a Beatmap; I don't use any click track. Any time I count off, it's just in my heart. Sometimes I'll go off the feel of a crowd, like if they way they're bouncing is a little quicker than the song, I might kick up the tempo a little bit. I see where the crowd is at. It's nothing drastic, but all the tempos are from my internal clock.
I play guitar all the time, and I'm constantly thinking of songs... Every time I pick up a guitar, I come up with different riffs, all different bands I've been in. Sometimes there is a song or riff that could only belong with Slipknot, and I just can't use it for anything else, regardless of whatever happened.