By the time your ape is dealt lethal damage, his sprouting is also dealt lethal damage, and SBA's will have seen both creatures with lethal damage and put them both in the graveyard before he has a change to sacrifice his creature.
(Prior to M10 this could have worked, since combat damage went on the stack, but this is no longer the case)
If an opponent attacks with a 6/6, and I block with two 3/3s that have first strike, how exactly does it play out?
Once you both pass priority while the stack is empty you proceed to the firststrike combat damage step, where your 2 3/3's deal damage to their 6/6. SBA's are checked, and the 6/6 is sent to the graveyard.
You just got very lucky. It has 4 targets, the 3 in his graveyard and the 1 in yours. A spell or ability only fizzels (is countered upon resolution) if ALL of its targets are illegal. 1 still is legal, so it resolves and does as much as it can. You get your creature.
Activated abilities are always Cost:Effect, O-ring is in fact triggered. Note you can still NAME oblivion ring with pithing needle, it just won't do much.
Your confusing land and mana. Land IS NOT mana, lands tap for mana. The stone adds all colours of mana to your pool, not a land of each type, its no different than if you tapped a mountain, forest, island, plains and swamp for mana.
No, you can only sacrifice a creature once, so you can't pay the cost for the tokens ability and still have the tokens around to sacrifice to the eruption.
Magma Phoenix' ability triggers as it enters the graveyard, by that time the Collar is no longer equipped - so no.
That is entirely wrong. When the phoenix dies it uses last know information, seeing the the phoenix had lifelink and deathtouch at the time it does apply. It doesn't matter that the phoenix in the graveyard doesn't have the equipment, the phoenix in the graveyard has nothing to do with the one that was on the field.
(Prior to M10 this could have worked, since combat damage went on the stack, but this is no longer the case)
Once you both pass priority while the stack is empty you proceed to the firststrike combat damage step, where your 2 3/3's deal damage to their 6/6. SBA's are checked, and the 6/6 is sent to the graveyard.
Sacing is part of the cost. And yes they could, in responce to your seismic shudder, sacrifice them and get the mana.
Edit: Yes they CAN deal more than one damage to the bird if they really want to.
That is entirely wrong. When the phoenix dies it uses last know information, seeing the the phoenix had lifelink and deathtouch at the time it does apply. It doesn't matter that the phoenix in the graveyard doesn't have the equipment, the phoenix in the graveyard has nothing to do with the one that was on the field.
It is however made clear that he's talking about the permanent exiled being counted as his white permanent, which it is not.