1. LED lighting would work but doesn't penetrate very well and mothers tend to get big which would make them real lanky, I think it would be better to use multiple cfls or a T5 (seen some nice grows with T5's)

2. Yes you can keep them in 24 hours light for vegatative stage. 18 on 6 off would work too or anywhere in between unless you have an autoflowering strain or very light sensitive strain.

3. You can use the same light but clones dont need too much light before they are rooted and in pots so I would keep them further away unhtil they have developed a good root system and in pots.