No, you're right, I'm not breeding, but I read that if the mother was originally a cutting then you shouldn't use it for more cuttings when it matures,
It probably does create less vigorous plants, at least if you clone a clone of a clone of a clone of a clone ...
The most I've done is three "generations". I haven't harvested yet, but the health and growth of the plant looks excellent.
Yes you can. are you talking about a rooted cut? I wouldnt take cuts of cuts of feminised plants. But for certain from regs, infact i advise it. You can only really tell how stable the plant is by a 2nd or 3rd generation clone/plant. Just make sure whatever you take the cut from is vigorous and healthy.
Guano varies a lot. Some is high in 'N', some is balanced, and some is mainly 'P'. Picking the right one to meet the needs of your soil is step #1. It can be mixed with soil, top dressed, or made into a tea. I use it as an amendment when building soil.