Do you have to ask people? do they just come by themselves over time? can you kick people out? will people from other factions join your settlement and do some sabotage related things? will they add their own flare to their personal homes? can you give them responsibilities to go out and do tasks, whether in your settlement or in the wastelands? can you have an army and take over other towns? what do you guys think?

Hot babes and booze.

hah yeah. have a club with rules such as "no guys allowed except me"

changed accept to except. i dont want no grammer nazis in this thread

I imagine there will be three main methods.

Invite a non-essential npc directly

Hire guards from some place

Put up notices in other settlements and random settlers/traders will come in on their own

Could be that if people see a settlement going up, they want to see what it is. Perhaps they are fleeing raiders and ask you to take them in?