People usually re-veg their plants
after harvest, not in the middle of flowering...During flowering it's usually clones that are taken and then re-vegged. I've done this myself
You could do it though if you really wanted too..you'd just have to chop things back like in the link below. They're looking so fine though, it would be a shame
If I was in your shoes I would try to be a bit more patient and just wait until these ones are finished flowering and then start the other ones all together..or get a second tent like you mentionned.
Since this is your first grow it's a learning experience and you should follow the process all the way through before moving on to bigger and better things imo
Rushing things and wanting more and better isn't usually the best approach to anything. Patience is the key...
Here's the revegging guide
http://www.weedguru.com/forum/viewtopic ... 88&t=26659
Scrog will be tricky if you haven't weeded out the females cause all the branches get intertwined under the screen. LST would probably be a better option