First, I would like to talk about tea. The wiki makes it sound like the quality of the tea only affects how fast you gain the bonus, and the bonus learning ability is always 20%. However, that is not the case at all. I have tried with very low quality tea and Q 90ish tea. In both cases I need 0.4l of tea to get to 100% effect (about 13 minutes). However, the bonus to Learning ability has increased significantly with the higher quality tea.
Second, I would like to talk about Hemp buds. The wiki makes it sound like the quality of the hemp bud does not affect the FEP gain bonus
The gain of FEPs is ~10% above normal.
However, I have heard different people saying that it does affect the FEPs gain (just as Tobacco affects the psyche bonus, for instance). Unfortunately this isn't something very easy to test, as there isn't a "FEP gain" box.
I will post more as I remember them. Please, help discussing these matters and posting new ones so that we can possibly improve the wiki.