When a read the description of a half action, it says that firing once is a half action... since ou have 2x half action... can we fire two time as a single shot each time ??

Nope. Although firing takes a half action, you are limited to one attack action per round. Although you will have a half action left after taking some combat actions, it cannot be used for an extra attack.

so in the same round i can point ( h/a +10 to hit) and shoot ??

I assume by point you mean aim and shoot, the answer is yes you can, just remember that semi and full auto are full actions. Also you can't shoot twice because the rules state you cannot do the same action twice in a round.

unless you do it as a multiple attacks action which takes a full round.

Essentially this is 2 attacks in 1 turn, 1 with each hand.

no relevant talents gives a penalty to attack of -20%/-40% (main/offhand)

only ambidextrous removes ofhand penalty to -20/-20

only two-weapon weilding is -10/-30

ambidextrous and TWW is -10/-10

only with pistols, having gunslinger, ambidextrous, and TWW is -0/-0 (no penalty)

You can make melee attacks with your main hand using swift attack and lightning attack also with this action. Along with a single attack with your offhand.

I don't remember the rules right now for semi and full-auto with each hand. I think that is possible also. So you should be able to full-auto with both hands as a full turn action.