Bonky makes a good point about the wiring. Setting that up I'd want minimum 40 amps at 240v goin into a sub panel in there, but 60 would be better. Looks like fun. I'd wall in the front porch to make a lobby entrance, that way the neighbors wont think they saw a nuke flash go off in your backyard every time you open the door. Otherwise maybe run tents in there.
In the main room I'd hang a 6" exhaust and filter in the peak and 2 x 600w HPS lamps, one on either side midway down the roof slope. I'd go hps because you can get them fairly close to the plants being so height restricted.
Intake air... That's a challenge in a shed. If your ductwork is inside and you dont have a lung room, the cold air in it will cause mad condensation to drip from the ducting. I chose to keep my Intake filter and ducting outside the shed, and put a backdraft preventer on it then mounted it flush to the inside wall. That way there is no interior ducting to drip from.
You dont want to go airtight sealed on a grow that size imho, dehumidifyers and AC and Co2 sniffers and regs and tanks and everything else would cost more than its worth for that scale I think.
A 6" inline fan plugged into an inkbird itc-308 temp controller will keep the temp. A small 40-60 pint dehu and medium room humidifier hooked up to an inkbird humidistat... off to the races.
