http://www.a1b2c3.com/drugs/mjgrow4i.htm#A28
This is a great information on the basics of cloning. Once you have the clone put it under 12/12 and you should determine sex in about a week or so.
I know that as a patient you can have 8 ounces of dried pot. If you where to go over your limit then you are suppose to sell it to a dispensary. I talked with one bud tender and they said that I could sell it to them with no problems. I have not done this yet but that is what I am...
Yes taking a clone from a plant and put it into 12/12 seems to be a good way. I have never done it personaly but alot of people on here do. Most of my grows come from clones.
As far as using milk jugs, I would go with a different container. Roots need to be kept dark. When you are getting your container make sure you have 1 gallon per foot of plant. If you want your plant to be 3 feet tall then use a 3 gallon container.
On Saturday I harvested my 420 bud. Hog's Breath. It looks like a few ounces but we will see when I get it all dried. It is going into glass jars till 420.
I have been doing some research with using swamp coolers for your grow room. As long as you put distilled water or R/O treated water in the cooler you will be fine. If you use regular tap water then you will get an Alkali build up. That in turn will blow on to your plants leaving a white film...
Just keep in mind that once you start your flowering cycle the plant will grow 2-3 times it's size. If you have 12 feet then you could vegg till it is about 3 feet tall. If you wanted to.
You can build your own carbon filter with parts from Home Depot for about $30 to $40 dollars. I built one and it works great. No smell what-so-ever. Here is the thread.
https://www.rollitup.org/indoor-growing/7074-easy-build-diy-carbon-filter.html
It takes about 3-4 weeks vegging before you can determine sex. As far as when to start flowering That depends On how much room do you have for flowering. What strain is it?