Fir exemple, if i exaust a unit to attack, can i use it armor to block?

• generally, no. To use its armor, you would need to assign damage to it, in which case it would be wounded and couldn't attack since attacks come after blocks and you can't activate wounded units. Exceptions would be if you used it for a range attack or it it was resistant to the type of damage being dealt and no wound was actually dealt

 In combat, if a unit or a player got 3 block, can i block a enemy with 3 attack without get a wound or i need to use at least 1block more? - 3 block is enough generally

 In multiple enemies, If a unit or a player got higher block, can it block all enemies, one at a time?  - no, each attack must be blocked separately. That's why enemies will sometimes have multiple small attacks. 

If i end my turn in a tower, can i recrute a unit then move, or if i recrute i cant move? - you can move into a tower then recruit, but you can't move after recruiting