STR & MAXHP are both functions of Level, which is a function of EXP,
so yes, MAXHP will increase as the STR increases, as long as both curves increase with each level.
If you're talking about adding an additional bonus to MAXHP with the STR bonuses from weapons & armor,
You will need to define the formula. i.e. MAXHP = base_hp + (str_plus * C)
where base_hp is the MAXHP from the actors curve in the database,
str_plus is the STR+ from the weapon or armor,
and C is just some constant to multiply the str_plus by.
It's up to you. I've never played warcraft, so I have no idea how it works there.
Be Well