If I were to block a 7/7 with trample with 2 creatures say a 0/5 and a 4/3 (each enchanted with {Gift of immortality})
Can opponent choose to deal damage to only one creature and the rest hits me? Or must they deal lethal then deal the rest to second creature?
He must deal enough damage to each creature to kill each one before it can trample over.
Trample creatures have to assign lethal damage before they can deal damage to a player. The 7/7 would have to deal 5 to the 0/5 and 3 to the 4/3 before it would be allowed to deal the rest to you.
However, if it had deathtouch it could assign 1 to each creature, count that as lethal, and deal the rest (so, 5) to you.
The relevant rule:
702.19b (http://imtgapp.com/forum/index.php?action=imtg;area=rule;number=702.19b): The controller of an attacking creature with trample first assigns damage to the creature(s) blocking it. Once all those blocking creatures are assigned lethal damage, any remaining damage is assigned as its controller chooses among those blocking creatures and the player or planeswalker the creature is attacking. When checking for assigned lethal damage, take into account damage already marked on the creature and damage from other creatures that's being assigned during the same combat damage step, but not any abilities or effects that might change the amount of damage that's actually dealt. The attacking creature's controller need not assign lethal damage to all those blocking creatures but in that case can't assign any damage to the player or planeswalker it's attacking.
Example: A 2/2 creature that can block an additional creature blocks two attackers: a 1/1 with no abilities and a 3/3 with trample. The active player could assign 1 damage from the first attacker and 1 damage from the second to the blocking creature, and 2 damage to the defending player from the creature with trample.
Example: A 6/6 green creature with trample is blocked by a 2/2 creature with protection from green. The attacking creature's controller must assign at least 2 damage to the blocker, even though that damage will be prevented by the blocker's protection ability. The attacking creature's controller can divide the rest of the damage as he or she chooses between the blocking creature and the defending player.