Got a few of questions regarding settlements, size limits etc.:

1. How many settlers can any single settlement hold? more specifically how many can Spectacle Island hold?

2. Do companions or former companions assigned to a settlement count as "settlers?"

3. Why are some but not all locations available for reassignment when sending settlers from one location to another?

4. Can I reassign a provision supply line after it has already been established?

5. What determines how many caps a settlement generates when you open "stores?"

6. How do I assign myself a bed?

7. Is it possible to assign settlers to wear power armor?

Which location in your opinion is the best place to establish your base and why?

2. Yes

6. Not sure you can other than making sure all of the settlers have been assigned their own bed first.

7. Yes or so I have seen in videos but I have not tried it.

Not sure about the rest. #1 has to do with your charisma score but I don't know enough about it to comment more.

1. 10+charisma, this updates when you save in a settlement, or load, so if you boost your charisma with chems, cloths and save in the settlement you can remove that and the settlers will continue filling to the boosted amount, I believe the very max pop is 41, but if you got the bobblehead before reaching 10 cha then it can only reach 40.

3. population limits

4. You needs to wait at the settlement until the actual provisioner shows up and enters the settlement, which can take in game days.

5. Population (including population in connected settlements), happiness, supply depots, level of the store,

the stores income happens after both one in game day, and eight minutes in real life happen, so waiting a day in game does not update the store until real time passes, and wandering the wasteland will pass the real time without updating until an entire in game day night cycle has happened.

6. Can't be done, only manually assigning settlers that choose the wrong bed.