Congrats on your first grow, Ryno! It looks like a decent set up as far as size, lighting and such.
to try and answer a ? or two...

I wouldn't put milk in the soil. Ir might smell and attract bugs and stuff.

You can LST when the plants are large enough to bend a side branch 90º or so.

I would top mine at 4-6 weeks or when your plants are 6 node or so.

THe best advide I think is to read a lot of threads on the subjects you are interested in. Read a lot. Get a book even.

Best of Luck!

Shovelhandle