Here Are some info
Add on decks.
http://paizo.com/threads/rzs2v6py?Best-Class-Deck-addon-for-Red-RavenAric
And here Also
Intrigue deck.
http://paizo.com/community/blog/v5748dyo5lks1?Ultimate-Intrigue-Deck-Previe w#discuss
Aric/The Red Raven is a pretty complex character, and not one I recommend for new players. He interacts quite closely with specific rules situations, but I'll answer some of your questions as best as I can, in brief.
1.Eric have 6 cards on hand, Ravin have 4. What is working the change between characters and about this quantity of cards?
Your hand size usually only matters at the very end of your turn, when you reset your hand. You reset your hand AFTER apply any other end-of-turn effects, and when you reset your hand you have to draw up to your hand size (or discard down to your hand size). This means that ending your turn as Aric will leave you with more cards in hand, and more options to play with.
Switching your character token mid-turn will not change the amount of cards that are currently in your hand (though it will let you exchange one card with a card in your Kit).
2.Yes, this character have one kit with 3 cards and could be used to change between Eric(Human) and Ravin (Avenger).
The Kit doesn't allow you to switch back your card tokens, it just gives you an extra stockpile of cards you can draw from when switching back and forth. This is so that you can have the right cards for the right character - having weapons that require proficiency aren't that helpful in Aric's hands, but excellent in The Red Raven's. A lot of allies aren't that helpful for The Red Raven, but are excellent for Aric.
3.Eric is better to find Ally, Item, Bless, (boon) while Ravin is better to find barrier and monster (Villan, Henchman)
As a general rule of thumb, yes. Aric is better at acquiring boons and exploring faster, and The Red Raven is much better at fighting monsters and is better against most barriers. (Some barriers will be better dealt with by Aric with Knowledge checks, but those are rare)
4.If I decide use Eric for my first exploration on location and found a monster, what´s the procedure to do? I could fight with monster if I have weapon like Eric or I need using one card of my kit and change to Ravin to encounter the monster?
You can only switch characters back and forth when a power lets you do so. Originally, they can only switch at the start of their turns, and in the process they swap a card with one from their Kit if they want. (Note; This means the Kit will always have exactly 3 cards in it, no matter what)
If you want to swap your tokens mid-turn, you'll need to use a specific card effect (Mask of the Red Raven, an item) or you'll need to take the Power Feat(s) that let you switch when you examine a card in a location deck. A strong strategy is to use cards like allies that say "Examine the top card of your location deck, then (you may) explore your location", like Psychic Investigator, so you can do something like this.
1. Explore normally (preferably as The Red Raven, because he can handle combat checks easier).
2. Discard a card like Psychic Investigator to EXAMINE the top card of your location deck. It's an ally with a Diplomacy check to acquire in the deck!
3. Use your power (if you've gotten the power feat) to switch your character token so that you're now Aric.
4. Psychic Investigator lets you explore, now that you've switched to Aric.
As you develop more feats, being able to examine cards before you encounter them is essential so that you can switch into the right character for the right purposes. As a general rule, though, on your own turn you should always stick as The Red Raven because Aric is very, very poorly suited to combat (which is a major part of the game).
Could you give me details, like a simulation step-by-step about one round and your variance/possibilities?
That would be more complex. As I said, I generally recommend sticking as The Red Raven early on, and then switching back and forth based on Examination effects once you can. If you end up having to fight as Aric, you'll usually need to discard weapons or get additional support (like blessings) to have a decent chance at passing combat.
However, Aric has a much larger hand size, an amazing Diplomacy check (which can be leveraged with boons like Quick-Change Mask in the Ultimate Intrigue deck) and is generally better at exploring with allies and acquiring boons.
It's also expected that occasionally Aric will run into a combat he can't deal with, and just evade or take the damage then come back swinging as Red Raven.
You use both sides, switching as you switch guises.