The better man? There is no such thing [base class]

[RoyVG]

This is the first time I have taken a good look at this class, and all I can say is, great job. I'm currently building one, and looking throught ther Teratomorphs, I noticed something with Size Increase I.

Size Increase I says that you gain a +2 bonus to Strength and the benefits and penalties as indicated in the table. When changing from Medium to Large, does that mean you gain a +4 bonus to Strength in total? And changing from Huge to Gargantuan would give a +6?

Also a few small questions about the Quills mutation. It counts as a natural weapon, so if you increase your size, the damage should increase as well, right? So 1 becomes 1d2, 1d2 becomes 1d3, etc.
Second when combined with Impale, which damage does the impaled victim take, the 1 damage from the attack, or the 1d4 listed when removing Quills?
Third, is the nemy impaled by 1d4 quills or just 1 for damage purposes?
Finally, does the Thorns Mutation in the Plant section also apply to the Quills?