Hi, I have found 3 bobbleheralds so far, do I need to keep them in inventory to activate the perk or I can sell them or drop them because the perk was activated by automatically? Thanks.

Place the bobble heads on your bobble head stand crafted in the work shop

I don't have a settlerment yet but thanks, I will keep them for later

Well you don't need a settlement, just a work bench (the red ones) which can be found in a fair few places.