Core Rulebook, page 159, has the cost for hirelings. They are also mentioned on page 163.
Hireling, Trained: The amount given is the typical daily wage for mercenary warriors, masons, craftsmen, cooks, scribes, teamsters, and other trained hirelings. This value represents a minimum wage; many such hirelings require significantly higher pay.
Hireling, Untrained: The amount shown is the typical daily wage for laborers, maids, and other menial workers.
Trained hirelings cost 3sp per day, untrained cost 1sp per day.
I don't know if any Pathfinder book deals with slaves, but the Conan d20 book uses the following prices:
Slave, female, beautiful: 60gp
slave, female, common: 30gp
slave, female, high-born, educated, beautiful: 150gp
slave, male, rebellious savage: 5gp
slave, male, work-shy criminal: 8gp
slave, male, hard-working, submissive: 15gp
PFSRD also lists costs for different types of slaves, ranging from 50 gp to 500gp.
Apperently from Adventurer's Armory.
How many can you have? Is there a limit other than gp to how many hirelings you can have at any given time and will they fight with the party on an adventure?
If you hire soldiers/mercenaries they might, but those will cost significaltly more than 3sp/day. (those are min wages only)
Especially if you don't want them to be level 1. Also if you have a reputation for hiring cannon fodder with a 90% death rate, you'll get trouble finding more.
How many can you have? Is there a limit other than gp to how many hirelings you can have at any given time and will they fight with the party on an adventure?
As many as you can manage without them running away or revolting, I guess?
Oh wait, you asked about hirelings.
As many as you can afford, but they aren't going to fight for you at that pay grade. Look for mercenaries. You'll get less XP, and they may want a cut of the loot as their pay.
If you hire soldiers/mercenaries they might, but those will cost significaltly more than 3sp/day. (those are min wages only)
Especially if you don't want them to be level 1. Also if you have a reputation for hiring cannon fodder with a 90% death rate, you'll get trouble finding more.
Yeah, that'll tank your Leadership score in my book.