Don't think it has anything to do with difficulty, but more the order of which the female characters are met in the story (could be wrong, though).

Ah, i'm pretty close to that one. The furthest off are Olivia and Cherche, who i haven't even started yet. Tharja, Cordelia, Maribelle, and Panne are all at C-rank, while Sumia, Nowi, and Lissa are at A-rank.

No, that wouldn't match. I have female avatar, Sully, and Miriel married off, and with Lissa, those are the first four women you meet in the game, yet i got numbers 8, 12, and 14. By your system, FA would be 6, Sully 7 and Miriel 8

I am starting to feel like the europeans, about the anxiety to play this game.
The release of the game in my country has been delayed 2 times already, the anxiety is killing me.
It was to be released 02/15, then 02/20, and now it is 02/28, but there is no confirmation.
Nintendo did something really wrong about the shipping manegement of Awakening.

Oh, one more thing, this will be my first fire emblem, any advices about gameplay?
I played the demo and had no difficuties on normal and hard, but on lunatic i cant even pass half the first stage.
So i will be playing on hard.

And about "Pair Up" i dont like this feature, is it really important? I get just a few bonus status but "lose" one unit while pairing, i dont see much gain.

It works like a "Rescue" substitute (although the person who needs rescuing needs to actively pair up with the rescuer, so it doesn't work for fixing a mistake made during a Player Phase), and you can use it to have units shuttle other units around (so mages can"carry", say, cavaliers through sand, or fliers carrying anyone anywhere), and you get a chance of double attack activation which can be very useful, though amusingly double-attack can screw you, like if a non-ranged attacker idles up to your unit in a chokepoint and attacks, where the unit alone might not have killed the enemy, you score a double-attack, the enemy dies, exposing you to more attacks that turn that you might otherwise have not gotten.

Good, just do hard on your first playthrough, it will be difficult enough to be challenging but still be fun.  Lunatic is another league of shit you don't wanna go through on your first file on your first FE game. 

Pair Up really isn't essential in Normal/Hard (heck it felt like cheating for me since I'm used to all the other FE's) but once I got to the recruiting the children chapters it was kinda needed cause of how strong the units were.  But still in the main missions you can get by without it.  On Lunatic you need to do it from the start or your damned.  The extra stats they give is needed cause the enemy has insane stats dispite their level and you attacked by hordes of them.  What I usually do to damper the exp the side unit gets is switch them everytime the front unit levels.  But then again I'm not an expert on Lunatic since I'm only on Chapter 6 Lunatic/Classic.

Did you learn of the weapon triangle from the demo?  If not Axe beats Lance, Lance beats Sword, and Sword beats Axe.  When I mean "beats" I mean an advantage.  If a Sword user attacks a Lance user then the Sword user has a reduced chance to hit/crit the Lance user, and the Lance user has a higher hit/crit chance on the Sword user. 

Bows and wind magic do triple damage to flying units.  Hammer's do triple damage to armored units (Knight, General, Great Knight).  Beast killer weapons do triple damage to beasts and mounted units.  I think that covers all weaknesses.

Almost all classes level to 20 and can be promoted using Master Seals (can be used as early as lv 10 if you want), and then level another 20 as that promoted unit.  Second Seals can be used at level +10 to reclass if you wish.  This is usually used to either obtian skills from other classes or have more levels in which to get more stat ups.  You can reclass back to their original class, they will remember their skill levels in weapons/tomes as well.  Special classes level to 30 and do not promote and usually cannot be obtained from normal units trying to reclass.

A guide to all the classes is here:

http://serenesforest.net/fe13/class.html

I guide to all the skills is here:

http://serenesforest.net/fe13/skills.html

Both are spoiler free as they are blacked out.

you will see how important it is.  Sometimes i do almost the whole mission in pairs!

Thanks for all the advices guys.

@crazy_man, no i didnt know about the weapon triangle, thanks again.

Since i only have the demo to play, what strategy should i try to complete the first stage on lunatic?

Hey, at least you have the demo >.<

But perhaps try pairing up units and see how that works?

It is partially necessary, in one part to increase Support chances and in another because taking on foes straight up early on is difficult... at least in Hard mode (which of my two saves is all I've played).

It gives some of your wounded units a chance to still be effective by boosting another units stats, you sort of miss the Rescue option as there is no way when you pair up to get the character initiating it to be the main without the other unit having a turn left as another poster said leaving some units out exposed when you make a mistake but it makes for some great encounters when you get two or 4 attacks or a critical support block.