Heat issues - check, inline fan works great. When you set up your fan, pull through the carbon filter, don't push against it.
Fire issues - smoke alarm + extinguisher or ready bucket of water.
Nutrients - cannabis can grow really well if you leave out the green GH veg nute and only use micro and bloom. This style is called the Lucas formula and can be searched in google. The GH instructions work fairly well at 1/4 or 1/2 strength for autoflowers, but full strength feedings will be too hot. A good pH and ppm meter will help you get dialed in if you don't already have those. I keep my feeds around 200 ppm for little seedlings, then go up from there in 100ppm increments as they mature.