The largest classification subgroup is the group "kingdoms." As the domain is the most general classification and the starting point of classification, kingdom is the largest as it's the first subgroup.
General Works falls under Generalities, which is class 000 of the Dewey Decimal Classification System. Examples include: 000 (Computer Science general works), 017 (general subject catalogs), and 080 (general collections).
No, rabbits are unable to throw up. This is why rabbits to do not need to be fasted (starved) before having a general anesthetic, as they are unable to vomit there is no danger of them choking on vomit in surgery.
There is NO opposite for species (a taxonomic classification). However, the opposite taxonomy of species and subspecies (the narrowest classifications) would be a kingdom (the most general classification).