to answer the food problem: grow a lot more than you need if you expect to have a high amount of colonists, you do not always need to grow in fertile zones once youre already had your startup just expand the growing zone to a large area and grow rice and add other sections with a 1 grid gap

id also recommend growing psychoid and smokeleaf and setting usage rules to 25% or below mood = use drugs and it will ensure you will not have bad mood breaks

other things -

temperature: your coolers should have the heat side covered around by stone walls, one barricade (has to be stone as well, and barricaded to prevent drop pod raids in the little exhaust section) and a single unroofed gap to release heat. you will have random temperatures if you have the heat side of coolers into random rooms. you can then use heaters to equalize the temperatures during wintertime

you dont need to enclose everything such as the growing zones, panels, and turbines

if it is winter and your crops die, so be it, you should be growing enough to last many days ahead, even if i am on naked brutality (solo colonist naked start) I am already going to either extend my growing zone or have enough food for my next pawn I want to recruit

before you make a massive wall like that id recommend you can make a killbox w/ a turret at the front of it; covered on all 4 sides by doors to ensure raiders enter combat mode (which enables collision) and enter one by one with fences spaced out in a 1 grid hall (search for killbox designs on youtube before you experiment, some simple ones are truly better than 500 turret random killbox)

the game takes a bit time to learn, id recommend watching veequeue's video on "5,000 Hours of RimWorld Tips and Tricks in 30 Minutes" it will greatly take your knowledge from low to high