Buffs that can be acquired through camps cycle every 30 seconds from the time they are deployed, and if a particular camp has multiple tiers of buffs, they will change to the next highest rank if applied to an individual with the baseline rank.
The buffs will only be applied to people on your team/raid that are within sufficient range. Players not in the deployer's group will NOT receive the buffs.
Merchants and services placed by certain camps (vault, mail, etc.) can be accessed by anyone, even those not in the group, unless the merchant has other restrictions on who may access them (in the case of faction merchants deployed by faction-themed camps). As stated above though, the buffs will not hit players that aren't in the initiator's team.