I think there's also some cheese with those Necrotic Cyst spells. I forget what they do though.

Turn you into an undead tumor if I remember right.

Necrotic Cyst gives the target penalties against saving throws from schools of Necromancy and target takes more dmage from undead.

Necrotc save or die spells turn the person into a Skulking Cyst which is a mass of rotting internal organs that carries around it's corpse of the dead body it ounce was.

I have a question about using monsters as races.

Say I can make a character with an ECL of 6. I want to make a bugbear fighter. The level adjustment for bugbears is +1, and it has 3d8 hit dice. Does that mean the ECL for bugbears is four, and I can create a level 2 fighter?

Yes, exactly right.

Do you have to choose the exact terms of a spell when you prepare it for a readied action?

Any readied action will typically need some DM adjudication, but typically you do need to be as specific as possible. You shouldn't just say "I'll cast a spell when I see my enemy." You should state the spell and any details that might apply. Rather you'd need to say, "I'll cast color spray when my enemy is within range."

Or even, "I cast color spray when a bugbear gets within range". GMs can be as strict or as loose as they prefer.

Does magical protecton, such as that from Rings of Protection and Bracers of Armor, stack with AC bonuses from armor?

Rings of Protection gives Deflection Bonus, so it stacks with armor (but nothing else that gives deflection). Bracers of Armor gives Armor bonus, that doesn't stack with armor (obviously).