1. Yes, flowering should be more than 40 days. Trichomes age differently just like leaves do and may in some areas turn colors. It is apparent you have few trichomes as you can count them>???? That is the impression I receive anyhow. Heck you should have so many that counting is out of the question. I see this as some other sort of issue in the plant.

2. Nitrogen bearing nutes will leave a very nasty taste in product unless fully flushed. Just get some Fox Farm Ocean Forest. Shy away from production potting mixes as they have high N additives, which really isn't needed in flower.

3. Light allows the plant to nourish itself and grow. You can grow awesome weed if you use enough of and the right kind of light. You still need a good medium such as Fox Farms OF. Not too much water. Proper timing of lights, enough air, and you shouldn't need any nutrients, just repot every 3 weeks with a size up pot and more OF.

LIGHT HPS for flower At least 400 W 1 foot away from the closest top. Maybe 16 inches to be safe if heat issues occur. Air circulation is important too