I have noticed that some of my settlements grow larger / attain more settlers faster or get happier faster than other despite me building pretty much the exact same stuff (similar amound of food, beds, shelter, furniture, defense etc.)...

Do we konw what exactly contributes to the growth rate? At 80-85% happiness im also not entirely sure how i can increase the happiness rating (or if i should care at this stage)?

Moreover, im wondering if its worth/useful to build the same/other stores in all my settlements or if they work similar to workshops such as that you can them all build in one settlement (i assume that you should build them in every settlement).

I'm sort of wondering the same thing.

My settlement has acquired 2 new settlers since I put up a radio beacon. I think that is probably one of the main factors. Also depending on how much food and water is available is most likely another major factor.

For the first time I set up a trade route between Sanctuary and Green Top(i think it's green top)? That may be another happiness factor?

im just wondering cause my third established settlment - despite having lower happiness is growing faster than my second and will soon have the same number of settlers as my primary settlement which seems to have stopped growing despite this being 1 settler short of the max i can have (if this is as i have heard 10+ charisma rating)

Food, water, beds, and radio beacons contribute to settlement growth. Power doesnt contribute to growth, because places can certainly function without it, but it does contribute to happiness.

is it just power access in general or do you need to have furniture that actually uses the power?