MTG: Regeneration?

Question

This is what I know about regeneration: It keeps the creature from dying. It taps the creature. It removes the creature from combat.

Are the following scenarios correct?

1) I have a River Boa; my opponent has a 1/1. I attack with River Boa and he blocks with the 1/1. I want his creature to die; I want River Boa to live. Can I achieve that by doing this: River Boa attacks, 1/1 blocks, Damage goes on the stack, in response to the damage going on the stack, I pay G to regenerate River Boa. If I do this, will his creature die and River Boa survive?

2) I have River Boa, opponent has a 3/3. Opponent attacks with 3/3; I block with River Boa. I want to keep River Boa alive, but I don't want the 3/3 to get through and damage me. Can I achieve that by doing this: 3/3 attacks, River Boa blocks, put damage on the stack, in response to damage, pay G to regenerate River Boa. Will the 3/3 remain blocked even though the river boa is removed from combat?

Answer 1

yes, both scenarios are correct, unless your opponents 3/3 has trample.

Answer 2

1. The 1/1 dies and the boa survives.  The combat damage is dealt and then the regeneration hits after the damage is dealt, bringing it back to life.

2. The boa survives and the damage does not go through.  The boa takes all 3 damage, then the regeneration happens and the boa lives again.  If the 3/3 had trample, the boa would take 1 damage and the other 2 would trample over to you.  But as is, the boa takes all 3 damage and lives to islandwalk again.