Dust crickets daily with calcium and once a month with vitamin powder (rep-cal is a good brand)

Yes, they do need uva/uvb lighting. Bulbs don't cut it (for heat yes, but you will need a fluorescent tube to take care of the UV lighting)

You should know that it is very stressful for chams to live with other chameleons.. they are very territorial.

I'm not sure how big flapneck chams get, but a nice large screen cage will be appreciated by your little guy/girl. I used a reptarium for my Jackson's cham when I had him, and it's really a nice cage.