spiders are not a problem, they are one of the most beneficial insects to have. spiders in the garden = a healthy garden. as for your main concern, yes yes yes use flower nutrients! if you dont you will end up with light fluffy buds instead of the forearm size colas the sun is so good at helping produce. depending on your location and legality do yourself a mega favor and go get some high pk guano or bone meal or even better some cheap pre-formulated bottled nutrient made for flowering. roots organics, earth juice, neptunes harvest just to name a few. if you dont add flowering nutrients you are shooting yourself in the foot in the long run for how much time and energy and love we give our gardens. this is not to say it is absolutley necessary but unless you're running a "hot" soil I'm betting you dont have the necessary pk readily available. Also always use molasses at 5ml/gal every watering to stimulate the beneficial microbes in your soil. this will help with the uptake of whatever npk is in your soil. it is so watered down that the molasses is more likely to be used by the microbes before attracting a giant ant colony or whatever bugs are around.
good job getting some fems from your bagseed!
also neem is CHEAP like $10 at hdepot...