1. This is mainly a two player game. There is an official variant in the rulebook that let's you play with 3 or 4 players but IMO it's best with two. However this is a long and heavy wargame (although not so in the actual wargame genre) and generally not that popular among the ladies (please excuse my horrible stereotyping) so the bigger question might be whether or not she likes it...
2. Well, I'm not sure what you mean, but the basics are pretty simple. I attack your region with 8 dudes, and you have 3. Then we roll amount of dice per units we have, maximum of five (so I roll 5, you roll 3). 5 and 6 are a hits (= dead dudes). If we have leaders we can re-roll some bad dice. But there are variables: Defender gets bonuses in cities and fortifications so attacker hits with only 6. Strongholds (think Helm's Deep or Minas Tirith) are awesome deathtraps in that they can stretch the battles for a long while and give good defensive bonuses but at the same time the defenders are trapped and will eventually die unless help arrives or they can try fight their way out of there. It's very thematical. But the best feature are the Combat cards which are played at the beginning of the battle and gives the game much of it's fluff, for example the baddie plays 'Relentless Assault' which automatically kills some of his orcs but he hits easier. But at the same time goodie plays 'Heroic Death' on Gandalf which kills him but let's him substract 3 hits from his army. So already you got yourself a nice story there of orcs making a suicidal charge and Gandalf sacrificing himself to save his army.
3. The way you phrased that question makes me think you'll be disappointed. Depends how you define "well reflected". They are true to the books, and in the grand scale of Middle-Earth I'd say they are very well reflected. They generally have one or two passive skills but that's about it. They are not very flashy or memorable. For example Strider can hide the fellowship easier which makes sense for he is a great ranger. Gandalf the White can negate the leadership of enemy Nazguls in combat which could be clarified as a "powerful magic skill", but again, not very flashy. Boromir, Legolas and Gimli don't even have any special abilities to speak of, unless you manage to get their specific Event cards from the deck in which case they can somewhat ease the damage the Fellowship takes from a successful ring-hunt. So, you won't be playing "Gandalf's skill cards" in this game.
4. Depends what you're looking for. For me this is the definite Middle-Earth game. It captures that dusty "feel" of the books better than any other LotR game I've played. You're kinda manipulating the events of the world from a distance, moving grand armies and making grand plans. Each game generates a different what-if version of the original story and it fascinates me. But if you're looking for a more character oriented game, I'd say Middle-Earth Guest would be a better choice.