Right, you don't 'add up' the multipliers, you multiply them together.
So for heal pets,
Taming at 100 = 100% increase
Loyalty at 100 = 75% increase
So for a pet with a max heal of 20, with these skills maxed, the max heal becomes 20 * 2(taming) *1.75(loyalty)
This is an increase to 70.
Stalking will double this max heal to 140, but reduce the frequency of the heal. If you had a pet with a theoretical delay of 40 initially, the max heal would be 70 per 40 delay (1.75 per delay tick)
With stalking maxed out, this becomes a 140 heal, with a delay of 56 (if using whips). This works out at 2.5 heal per tick.
Of course, for a Beastmaster, you then have another multiplier, the class skill, giving *1.24 on all these heals (so for a BM, that 2.5 per tick becomes 3.1
Basically, all these skills that give bonuses to damage, heals, regen, experience  they all stack.
