Welcome to the Jungle!

Hey everyone. I have a big problem. I have 13 plants (3 Dutch Delight, 1 Strawberry Cough, 3 Blue Venoms, 1 White Rhino, 1 Lemon Skunk, 1 Hawaiian Snow, 1 Super Silver Haze, 1 California Hash Plant, and 1 Blue Hash) all under a 1000w HPS light in a 4ft X 4ft grow tent. I am two weeks into 12/12 and the growth has been more than I expected for the flowering stage. I should have started flowering sooner, but this is my first grow and I promised myself I wouldn't be impatient or overzealous. The ironic thing now is that I think i've been too patient and waited too long. There is severe overcrowding in the room and I am scared if I don't act now I will lose a lot of final harvest weight or experience diminished quality. I have an additional 400w of light I am going to add to help further penetrate the canopy, but I don't know if that will be enough. I have a great portable a/c, so temps won't be an issue from the additional light. My questions, for experienced growers who may have been through this, are........

1. Will adding the extra 400 watts be truely significant given the fact that the branches are so crowded together?

2. Can I tie the side branches of the bushier sativa plants in a somewhat vertical position to where they are closer to the main stem and take up less horizontal space?

3. Will tying the side branches as mentioned above effect my overall yeild or quality?

+Plus Rep for any helpful responses+

Come on guys, someone, anyone?!? I'm really trying to make this harvest as plentiful as possible so I can invest in a bigger and better grow room.

Nevermind for the lazy stoners who viewed this and didn't respond. I came up with a perfect solution. Everyone else is cool though.