Oncidium twinkle, spots and dried leaf tips
I bought this miniature orchid "Oncidium twinkle" in October 2009. It was a single plant with a spike about to bloom. It sent out 3 spikes one after the other and bloomed. The plant is under artificial lights. 12 inches away from four 40W fluorescent light bulbs. After that for almost a year, it has been giving out only leaves and I believe more plants. For the last few months, black spots showing up on the plant and the tips of the leaves have started browning. Two days back I noticed a spike coming up. I think it is going to give out flowers. Please see the pictures below. My questions are:
1) How do I get rid of the black spots? Why are they there?
2) The tips of the leaves are browning. Should I water them more often or increase the humidity.
3) It looks like there are a lot of plants there. Should I separate them? If so how do I separate them and what potting medium should I use? I don't want to kill the plants by separating them in the wrong way. Please let me know. Thank you.