Just about every question posed in your post is answered in FAQs and other posts already on this board. Spend a day reading through them so that you not only answer your own questions, but gain a thorough understanding of the process you seek to use.

In short, you will want to grow a few mother plants for taking cuttings. Harvesting every 1-2 weeks is much less practical than every month. I would also recommend not growing your clones to 14" before flowering as they will be large enough before growing to 2-3 feet tall in flowering (plus, that's not really SOG). For a true SOG, you would want to flower your clones within a few weeks after they root. The idea behind SOG is to have a flat, uniform, canopy of green, concentrating on the top cola for budding instead of the lower growth.

As for yield, that is so subjective it's not even funny. Look for the statistics on your particular strain; you should be able to find an approximate yield per square meter in SOG. If you use around 50watts of light per square foot and a SOG setup, you can expect circa 250-500g every flowering period (7-10 weeks) for a good setup.

Once again, do a little reading as it will not only answer your questions but may also give you a few ideas that you never considered.