Clamp lights are great. Also your cabinet should be made of wood. Cardboard burns so easily and the glues that are used to make it can be toxic when burned. Plus wood is a lot sturdier than cardboard.
Keep all plugs and wires off the floor and keep as much wire out of your grow area as you can. Never use duct, masking, scotch, or mailing tape for electrical work. Use wire caps (you can buy a big ass bag of them at the hardware store for a buck). Electrical tape is for temporary repairs and should not be used for anything perminent.
Wiring a large box with lights isnt a complicated thing, but you will need to spend money on the right equipment. The bulb splitters are fine, just keep in mind that the larger wattage bulbs tend to get heavy and bulb splitters are not the most secure things out there. Make as few wires spices as possible. Every splice is a potential short, shock, or fire. Add up your total wattage and use only wire that has a higher rating than your consumption. Most extention cord wire is good for 700 watts. Do not work with powered wires. Keep everything unplugged. Pay special close attention to not corss any wires. Most extention cords have 2 wires in them. On one part of the wire there should be some lettering embossed every couple of feet. Connect only lettered wire to lettered wire and non lettered wire to non lettered wire. Lastly, dont plug your set up directly into the wall. Use a surge protector.
You can buy the supplies you need at any hardware store and it shouldnt cost you more than $50 and 2 hours-bulbs not included.
For bulbs, you want to keep your wattage around 30 for each bulb. Anything higher and the heat from the ballasts starts to become a problem. More lower wattage bulbs effectively covers more surface area than fewer higher wattage bulbs.
I assume you know you want a higher ratio of cool bulbs (5000+K) to warm bulbs (2700K) for veg and the opposite for flowering. If you decide to take this advice, im sure the readers of this thread would be very interested in what you come up with.
Good luck, and do some research prior to doing things that are potentially dangerous.
