Your doing a great job cheezy!

re: Q1 & 2
flush them through with 6.5 - 7.0 ph water and aim for around 20% run off (adjust the amount of water until you are getting around about 20% of the total amount of water you've put in coming out the bottom... eg. if you pour 2l in at the top expect 400ml ish to collect in your trays... make sense?

let them dry out after a couple of days and then re-flush and continue to do so until 4 days before you cut them down.... (a little tip: let them dry out and do not water them for about 4 days before you harvest.... this will help you dry them quicker when harvested and also minimise mould problem when drying...

good luck... let us know what she yields