Hotter or longer?

Hi everyone. New to roasting my own beans, I am pan roasting at the moment. I know it's not the best way to go I am looking at roasters at the moment (UK) the options for a cheap starter one are limited.

My first roast I had tompan to hot to start with, second roast was a lot better. My first crack was not that pronounced though.compared to some videos I have seen on YT. The beans themselves after resting have a nice fruity taste they also have a strange after taste maybe abit grassy. I'm not sure. My total roast time was 18 minutes.

My questions are 1. How do I get a better FC? More noise and obvious 2. How can I give the beans more flavour and less grass!

Thanks