It is the number of that particular asset. In some maps (for co-op maps) you might see a total 4 jets for each team but that is including the jets operated only by bots as well, so there would be 2 player operated jets and 2 bot operated jets, total 4 (this setting differs on different maps and layers). You might not see all 4 jets being used by bot team in that particular map, since 2 of them are player operated and bots can't really fly them. So the reinforcements you are referring to are just the number of the particular assets that map has, and bots will only use the number of assets which are intended for them.
Score is calculated by various activities, if you are an infantry, you'll get score by capturing flags, killing enemies, transporting your squad by driving jeep or truck, building fobs, etc. Basically being useful.