sickness in the human game?

hm, im going to say no - there are no powers that would allow a character to be "invincible" to sickness, although of course the roleplayer can always choose that their characters never end up catching an illness. this would also apply to healing faster. not only do they extort the main game, but we also don't have a power for it regardless lol

yes, earth elementals can be used to grow plants and herbs! aesthetic elementals can also be used for this purpose and is more ideal unless you want your character to be able to control earth as well as it's much cheaper. this also applies to the animal rp as a replacement for flower prints

& to your final question, i believe so! i don't think they're in active production anymore however, so a character with asthma or diabetes might struggle to find what they need