Unlike other strength bonuses this is available to non-fighters.
I can't check right now but I'm 99.9% certain this is not the case. I'm pretty sure you *have* to switch to fighter before you can have the conversation that leads to his strength gain.
Actually I think you are probably right about this. I rarely play a lawful character so don't often get Vhailor's strength upgrade.
Although its not really a massive benefit given that you only get a free +1 strength from it (compared to the free +5 you can currently get).
Not sure what you're referring to here. In the vanilla game you can get anywhere between +1 and +3 strength depending on how Lawful you are. I wouldn't be changing that, it would just take you 1 to 3 steps up the progression in the case where that gain takes you through the exceptional strength tree. So if you are due the +3 gain and you are at 18/30, it would take you to 18/99.
Qwinn
I was meaning that free +5 strength you currently get (i.e. in an unpatched game) if you go from 18 or below to above 18 using Vhailor. i.e. +1 strength from Vhailor gets you from 18 to 19, but if you bought that upgrade via level up points it would take 6 levels. And if you got +3 from Vhailor then you would effectively gain 8 levels worth of strength (i.e. still getting 5 'free' points).