Need to increase internal heat of Cabinet in Cold Garage

hey guys .. I am building a supplemental grow cabinet to house mothers, do some occasional flowering / seeding , and cloning ... attached in the pics is a basic workshop table with 3 divisions underneath. both the sides and back and bottom are insulated panels ) I will have ducting running top and bottom at the back for air intake / exhaust ( I will be cutting into the duct in each of the flower and veg room and attaching computer fans. the ducts will end at the inside of the wall on the left (3rd) room where 2 more computer fans will be mounted (six fans total, two per room, out/in) >>> all this ducting leads to the right side of the cabinet where it is fed in and exhusted (two more fans ... I will strictly be using CFL's and floros and each room will have its own electrical outlet.
I was hoping someone will be able to guide me in methods of tapping into the duct with whatever attachment that might also assist in directional airflow (should I angle these offshoots?) or would a small squirrel fan on both intake and outtake ducts do the job completely . . yes i know about temperature differences and was thinking on maybe switching top for intake and bottom for outtake..
ALSo .. and more importantly though is I need ideas on providing any amount heat safely or at least helping in getting me temps to a satisfactory level. I am a few days away from testing to see what the base temperature willl be unaided, but FYI the garage is definitely at freezing or thereabouts currently (ontario canada)
I am open to any ideas that are fire safe.... thank you very much.

 

how much heat would a 75 0r 100 heat bulb put out if i were to utilize them?

 

Thanks guys ... all great advice ... the finishing details are also important i think i'll try the 75watt bulb in socket - i have socket plugs already. And throw in a bowl of water also for the humidity issues. The intake fan being substituted for just a vent i think is brillient - kinda avoids the blowing of cold air onto my girls - yes i know the rules of air dispersement ..but it just seems to be a gentler intake method. My water is not freezing yet so it's probably just a bit above freezing ...
Funny how this heat issue is the exact opposite to my other setup where I am 2 weeks away from moving my girls into my flowering room and i can't get the temps down to satisfactory levels. 2.5 x 3 x 7 enclosed room, 400W air cooled reflector with attached diy carbon filter. A 120 cfm inline vortex was first exhaust attemp, and a stanley blower was second atempt. i'm thinking maybe the intakes are insufficient. ALso I have about 20 ft of duct to vent through until it goes to the register outside. I Modded a stanley blower like so many people have graciously posted ... the only difference was i used sheet metal shears to cut the floor register duct so i could mold the opening to the exact size on the stanley. and attach with duct tape ... no spray foam required,

 

question concerning utilization of a 75w incandescent bulb for heating up my individual compartments .... will that light throw off the 12/12 or 18/6 cycles that the plants are on or should i use a green bulb or something else? thx.

 

whoa ... sweet .... it's like these things are custom made to each man's problem ..lol
I've read that marijuana plants cannot see the green spectrum of light thus using green party lights to see in the dark should also work for us in heating our rooms for alot cheaper? no? just wondering...