There has been no extended research on gramine (and substituted gramines) toxicity in man, we just know it's toxic to some animals. Better eer for the side of caution. You can check my signature link and the links therein, for a lot more information on phalaris, what strains have better alkaloid content, how to grow/harvest for best alkaloid content, and how to extract to prevent getting the toxic alkaloids.
Which virola are you talking about that has bufotenine? Some virola have dmt, or 5-meo-dmt too..
As for best extraction of san pedro/related cactus, a lot of people use 69ron tek, but you can do a normal A/B tek and use xylene or limonene as the non-polar solvent. If you do A/B, be sure to reduce well the acidic solution before basifying, it can help the yields, as opposed to too much water, because mescaline freebase is slightly soluble in water.
I wouldnt extract peyote just because they take so long to grow, I would probably get too attached to them before extracting, but in theory the same as for san pedro should work.