Two Level Undercurrent Veg Cupboard - Potential Problems?

I'm building a 3.1sqft (50cm x 58cm) 7.5ft (2.3m) high veg cupboard, split into two 1m high levels, with a reservoir underneath.

Running a 240w 301b LED split into two 120w individual grow spaces, about 39w / sqft.2 x 50L / 11gal tubs with 4 plants in each, with a 20L res under the bottom tub.
Not planning on running a carbon filter because I don't think there will be much of an odor issue.
Want an undercurrent setup, pumped up from a res underneath into the top of the top tub. Then 40mm PVC down to the top of the bottom tub, then draining into the res.

Never seen anyone with a setup like this before, and this is my first proper grow, so:

1. Do you anticipate any plumping problems? Should I use a bigger res to avoid accidental flooding?
   
   
2. Considering the pump is going to need to pump up almost 2m high what size pump do you recommend? (I have one rated at 850 L/Hr @ 2m but I was hoping to use that in my flower tent)
   
   
3. Will the 2 x 120w LEDs be overkill / too hot considering its just for veg?
   
   
4. Should I run separate ducting for the bottom space, or can I just cut a hole in the shelf for airflow to the top space, and up through the top of the cabinet? I'm guessing with good airflow the top space should only be a few degrees hotter.
   
   
5. At the end of veg I'm planning on just pulling the 4" net pots out through the lid, and putting them into their own 50L tubs in the flowering tent. Will I need to cut up the lid up in order to get them out, or should the roots separate and pull out through the 4" hole okay?
   
   No need to answer all the questions, any advice at all is much appreciated

Some pictures so you can try and wrap your heads around this wierd setup.

The lanky bastard of a cupboard I'm dealing with:


This is the kind of setup I'm thinking of, but scaled down:

Did you ever complete this?