Im for Mr Handy as your repair robot, I agree with the robots, just look at one thing - wealthy factions - as you said 1 robot no charisma so - 10 people + robots

and imagine 10 sentry bots, hell yeah, Solar is right 300hp is too much, bearing in mind they're armored and fire missiles. 200hp and only machine gun would be ok and only obtainable from slave master or whatever their name is

.
Im also against fuel for robots, again it would be a present for wealthy ones. Instead I suggest to give an option of Electronic Parts to be used on the robot/given to robot an initialise repair sequence/ or automaintenance without any materials, lets say 1hp/10mins with Mr Handy 80hp would replenish in 13hrs
@Solar have you played F2? there was a quest in sierra to build your own robot

AFTER-WAR goddamit, and dont tell me he was the chosen one ;P To craft robots (Mr Handy+robodog - only those, because they were popular in F2) one should need this robot motor or whatever it was in F2, obtained maybe from some robot encounter?
