All your questions can be answered by running a search on cloning and reading, but here goes.

You shouldn't put freshly cut clones on a 12/12 cycle for a couple weeks, but you don't need to have them under an HID light either. Putting the clones under 24/0 gentle light (a few inexpensive 23w 6500K CLF's will do) will allow the roots to develop better and once roots are established you can then go to 12/12 if you want...if you're doing a SOG grow...if you're not doing SOG, then they should be vegged for awhile...anything from a few weeks to whatever height you want.

You don't want to judge your potential clones on branch length alone, go by nodes...3-5 nodes from the end of the branch make a good clone, I only use 3. 5" is just a guideline measurement. Yes, you can take multiple clones from one branch...you can take the whole branch and make it a clone or a single leaf and make it a clone or anything in between. I recommend you read about bonsai mothers and cloning here (http://boards.cannabis.com/advanced-...ms-clones.html) before cloning tho. Then read Gypski's thread about cloning...no link, so you'll have to actually search for that one! Happy Searching!