I'm not here to tell you what you can and can't do but if it's your grandmas house then you should respect her wishes. Mind you, 100 year old! f.. me! give her my congrats on reaching the big one :thumbsup: You get a letter from the queen in the UK when you hit 100.

Have you already got the lights or not yet? The better the lights, the more you will grow. You can get a HPS in a smallish cabinet if you can vent the heat properly. search the forums for "cool tube". The benefit of fluros is they don't get anywhere near as hot and you can put them really close to the plants, and not worry as much about ventilation. If you go with fluros then it's worth thinking about how you can move them to keep them close to the top of the canopy.

If you are looking at sorting out a cabinet then don't bother trying to aim natural light at it. Plan your cabinet as an enclosed space. You can always shift the pots into the sun. Not sure what you mean by closet... are they built into the walls?

Look up scrog - screen of green.. LST - low stress training, or tyeing.

How much do you want to grow?