If you tap Karametra's Favor, does that mana gotten from this card disappear on your next turn, or does it work in the same way than a normal Basic Land card?
If you attack or block with a creature, which has the Karametra's Favor, can you use it's ability at the same time when attacking or blocking with the Creature?
Can you decide not to gain more mana with Karametra's Favor, when you choose to attack or block with a creature it's attached to (do you need to tap the ability, since the card is attached to a Creature you tap by wishing to attack or block with)?
1) Karamertra's Favor doesn't tap, it gives an ability to the creature it is enchanting allowing it to tap for mana. This mana works just like any other kind of mana and empties from your mana pool at the end of the step or phase.
2) You can use the ability anytime you are able to tap the creature, so you can do it with blocking creatures and attacking creatures with vigilance.
3) If the enchanted creature is tapped to attack you are not able to use the ability granted by Karametra's Favor. You do not need to tap in order to block so you can still tap the creature for the granted ability after it has been declared as a blocker.