The cabinet is 5ft high, 4 ft wide, 3ft deep
So that's 12 square feet of potential "canopy" you need to light.
You certainly can grow good plants under 250W fluorescent, but if your goal is to completely fill that space, then 250W of fluorescent isn't really going to cut it.
As a sort of rule of thumb, figure optimal lighting is 50W/sqft using HID lighting, or 70W/sqft using fluorescent lighting (assuming good reflectors). If you do the math, you'll see pretty quickly why larger growers tend to avoid fluorescent lighting!
So ideally, for a space that large, you'd want a 600W HPS, though you could certainly get away with less.
With 5 feet in height to play with, you might consider subdividing the space into separate flowering and veg/seed/clone areas.
. I only want two plants in there. Both will be indica I can use more than two cords I just don't like a bunch of wires. ( I'm always paranoid of fire risks) I would like to have both my exhaust fans and my single intake on one cord and my four fans that circulate air on one cord. I just don't want to overload any plugs or circuits. I'll be making my own hood from sheet metal. And running all my lights on one surge protector.
Two plants is fine, so long as you understand that they probably won't fill up all your space.
What creates fire risk isn't the number of wires per se, its how they are run. Keep all electrical circuits up off the floor of your cab so water can't get on them.
Don't overload your transformers, and don't overload your circuit breakers. A few hundred watts probably won't do this. . .but it depends on whether or not anything else is being run on the same circuit in your growing area (ie any other appliances, etc).
Computer fans draw very little juice, they're not really a risk unless you way overload the DC transformer. I think its perfectly fine to run all your fans from one transformer, again, so long as it provides enough current.
