The FF Grow Big is not organic. I would advise against using any chemical\synthetic nutrients in conjunction with organic nutes in an organic grow. The only thing that makes it possibly not such a big deal is that the NPK for the Grow Big and AN Bloom isn't exorbitantly high - but both likely contain synthetic chelating agents (commonly EDTA), which is no good.
Guano should be micro-biologically active in it's own right, and it is also quite potent. Ideally you would use the high P guano in conjunction with something else that doesn't have much phosphorous at all and instead contains more significant amounts of potassium and perhaps a little nitrogen. Examples would be liquid seaweed or kelp meal (1-0-2), and
blackstrap molasses (1-0-5). Earth Juice also has a product called Meta-K that is just bottled sulfate of potash, 0-0-10, so it doesn't take very much. Aside from that they sell their own Hi-Brix molasses for plants with an NPK of 0-0-3.
I would use the high P guano in conjunction with a lesser amount of high N guano, along with blackstrap and kelp for potash. Some other guanos contain a better balance of N
such as Peruvian Seabird guano, which is about 10-10-2. Guano will also vary in terms of the amount of nitrogen it contains which is immediately available (soluble N), and that which is insoluble or released over the long term (course of a month). So if you have more than a month to go until harvest time it would be good to supply a bit of guano with a decent portion of insoluble N. Give only high P about a month before harvest. Don't provide any significant amount of any guano if you only have a couple weeks left to go, ideally none in the last few weeks because a single application will feed for up to a month and a half.
Also, would using guano and molasses in a regular dirt soil be less effective than using them in a,soil such as FFOF?
Not exactly sure what you mean by this. If you're referring to dirt\soil as in outdoors in the ground I can't imagine it would be much less effective if at all, although application rates might need to be a little higher. What happens with phosphorous in particular is that it tends to be tightly bound up in organic complexes in nature. Plant roots can only take up P as a phosphate anion, and this soluble P tends to wash away from the rhizosphere. But as long as the soil is healthy, the microbes living within it are capable of breaking away phosphate groups from organic complexes, mineralizing them so that they become plant available and/or retaining them inside their cell walls and thus keeping them within the rhizosphere.
Otherwise, the bagged potting soil you purchase isn't really dirt or 'soil' at all. Ocean Forest is something of an exception to this (as I'll explain), but still a ways from being 'dirt'. The great majority of other potting soils you buy are actually just soil-less mixes; they'll be based upon limed sphagnum peat and\or coco coir with perlite, vermiculite and\or pumice added to improve aeration, drainage\moisture retention and general structure.
The higher quality organic potting soils will contain humus (stabilized decayed organic matter) in the form of forest humus, compost or earthworm castings. They may also be amended with a number of all natural or organic ingredients which are rich in plant nutrients (as Ocean Forest is). Humus is very important for several reasons, and outside in nature good dirt\soil will have a fair humus\organic matter content. Humus retains nutrients and moisture, contains very important organic (carbonaceous) compounds known as humates\humic substances, and harbors a wide variety of the micro-organisms that help keep plants happy.
Ocean Forest contains forest humus, castings and vermi-compost, which makes it very rich in humus and organic matter. But, what really sets OF apart from other bagged potting mixes is the fact that it actually contains loam- sandy loam to be exact. Trying not to get too deeply into it, but loam
is dirt: essentially the ideal gardening soil. All soil in nature is comprised of some proportion of sand, silt and clay. A particle of sand is very large compared to a particle of clay, and silt particles are larger than clay particles but smaller than sand particles. Loam would be roughly 40% sand, 40% silt and 20% clay. Along with a good organic matter content this gives loam perfect texture, drainage and moisture retaining characteristics and so it is perfect for growing plants in. Sandy loam just has a slightly higher proportion of sand; it's incorporation into the mix, along with humus, is what makes Ocean Forest the closest thing to a true 'soil in a bag' that I am aware of.
Looks like I wrote much more than I planned on, hopefully some of that helps to answer your questions.