OMG, I tried Minergate and haven't been impressed so I have decided to download the blockchain and mine to a more convincing pool.

Last time I tried this I downloaded Mist and it started to download the blockchain but it was taking an age and I read that you can use the --fast command on the command prompt to speed things up. At this point I went to Minergate.

Now I have downloaded geth, run it with the --fast command and it has downloaded all of the blockchain. Its still running and continuously downloading new data.

I'm wondering what to do next.
Geth
If I close geth and re-open it tomorrow will it just catch up?
Does geth always need to be running and synchronised before a miner is started?
Do I have to use the --fast command again or can I just open geth.

Mist
Also, if I download Mist can I just open that instead?
Does it matter that I used the --fast command when, I suspect, Mist downloads everything?

Thank you for any help!