The thing to do is follow nature...
my cacti gets placed out in early spring in spots that will not have hectic sunlight until the sun's path moves later into the summer, so it might get a few minutes of direct sun, then a few minutes filtered through the palm tree's leave, and as the season progresses they get more and more sun until they can handle full sun all day. This require a little familiarity with your environment. I don't like the idea of growing plants under light much, I always end up visualising the coal reactor on the other end of the wire.... but you certainly can overwinter your cacti indoors especialy over there where it snows in which case you can probably let them go dormant and nearly dry.. Indoor grown cacti will never be as strong as outdoor cacti, and you can even see it visualy, hard grown cacti of the same species are often unrecognisable from their domestic brothers in terms of spines etc...
Oh yes, re extractions, it is only 3 simple steps on top of the tea making process you may allready be familiar with.
Basicaly the tea gets basified, and then xylene is added the whole story mixed up well, let to seperate and the xylene pulled off, you then make a mixture of 100ml distilled water and 5 drpos of pool acid (muratic /hydrochloric). now you put about a 3rd of the volume of xylene's acidic water in, shake seperate and pull off the water. water gets sprayed on to evap dish and left to dry, repeat acid washes till no more mesc percipitates out of the evaporation.
