yeah you could do multiple boils, filter, put liquid together and reduce, and then base etc.. This is called an A/B

Im not sure if FASIPA works with toluene, It does with limonene but Ive only read of FASA with tolu/xyl.... Chemically thinking, it seems in theory like it would work, but truth is only testing would say for sure.
as for FASI/FASA vs FASW, main advantage of FASI/FASA is that you wont need to evaporate so much water (like with FASW) because it precipitates straight out of the solvent. Disadvantage is the precipitation takes long and it will have significant amount of the tolu/xyl/limo contamination, so you'll need to wash or recrystallize that with acetone or IPA.
FASW is cool if you have a food dehydrator to evap the water, or if you just want to straight away get the freebase, because then you can add sodium carb saturated solution to the FASW pulls, put that in the fridge for a couple of days and retrieve your freebase that precipitated straight out of water.
99% IPA is what you want, yeah.
Which wiki page says 300ml water per 100-300ml solvent? That seems like way too much. I would say 50ml FASW (x 3 pulls) per 200ml is quite plenty.
When you make FASW, you will notice water dissolves it quite poorly. So when people say 2g, that is way more than enough, you'll add some FA to a quantity of water and shake like hell, and there will be plenty undissolved in the bottom. Just decant water away, and add more water to that undissolved FA (plus maybe a bit more FA just to make sure you are always saturating the water. In the end you can always just dry the undissolved fumaric acid and store it again)
And yeah in theory you can add molar amounts of FA but I think its better to add a bit more just in case for example there were small traces of the basified liquid which will neutralize some FA, or something of the sort. Having some excess FA is no problem because first of all when you convert to freebase it is removed, or if you want it as fumarates you can always wash/recrystallize it to remove excess FA.
As i said with FASW you need to evap all the water, it wont precipitate out of the water (except if you freebase, then yes, as I said above). With FASIPA theoreticaly there wont be water involved, you´ll just filter to retrieve the alkaloids, unless you use a bit of water to help pick up the crystals that might be stuck to the container and then evap that.
Good luck!