I have only used power armour twice - both times in the Glowing Sea just to avoid death by rads... Really don't see the need for it with my build. That being said, I do 'enjoy' collecting a full set of each power armour set, with each type o coating/paint....I'm nowhere near complete, I have only four frames and only 1 complete set (Raider II, which is trash).
Regarding ammo, I'm not having any issues there, havent throughout the whole game. As someone else said, focus on perks for increasing damage and focus on modding weps to get the best damage and accuracy from them.
Hazmat suit took care of the Glowing Sea but apart from a few occasions must admit I haven't bothered with the Power Armour - even now in my first endgame period
Minuteman, defending the Castle