A friend of mine offered me his Crysis 2 key as a way of thanking me for a favour I did him.

Before accepting it I want to make sure that I actually want it, which is why I have a few questions:

1. can I activate the key on my own Gamespy account?
2. can I activate the key on my own EA Origin account?
3. is there an online pass I would have to buy?
4. what kinds of pre-order bonuses were there and have they at this point become unobtainable to me?

If I'm missing out on pre-order bonuses (not matter how miniscule they might be) I'm not interested in this game.

* There are a limited number of activations (5), but yes you can activate it via origin, etc. If your friend no longer wants the game, de-activate from his machine. In any case two computers with one CD key (which is ok) cant play online at the same time....
* There is no additional expenses such as an online pass.
* There is the "Limited Edition" pre-order bonus, and activating requires a separate key that can only be used once.

What exactly does this code do?

Afaik. it boosts the player to level 5 and gives him access to the holo projector, exclusive dog tags and an exclusive weapon skin.

Is this the only pre-order/limited pack there is? Because I could still buy this code (in case my friend already used his) from someone who still has one and not miss out on it.

You could not buy it and still not miss out on it, imo. Yes, it's the only pre-order bonus.

If your friend doesn't want his account anymore you could ask him to give it you and then change the username and password
As for Origin, if it isn't already activated on Origin then yes you can activate it

Are these bonuses available through normal gameplay or exclusive to the code?

You don't miss anything from Limited Edition. There are still ppl that can't activate the code and use the bonuses. If you can take it for free, than take it. If you don't want it, give it to me. If have a friend in need.

About the bonuses:
-boost to level 5 - you can reach there very fast; play crash site.
-weapon skin - you can't even see it by yourself when it's on. Others will not see any difference. It's just for SCAR. And you will have a new skin for more weapons if you want skins, when you reach level 50, in a normal game (LE or not LE).
-hologram - you can unlock it when you play the game and get xxx kills.
-unique dog tags - there are no unique dog tags. It's the same dog tags that everyone has them. You will only get a new frame for them (the metal frame that surounds the picture). And this can be seen by others only in the lobby, between games.
So, nothing is so important to make you spend money on it.

Meh, I didn't accept his offer.

I'm sick and tired of this pre-order and LE crap. Sod off Crytek!

yeah I was slightly disappointed when I learnt the LE doesn't really give you that much, though you did get priority on preorders where I was if there was a shortage of copies. So I got the game from day 1 with no hastle, and they rang me at the store to tell me when to come in to pick it up .

The pouch useless, the game case, slightly better looking, the level 5 boost, I found slightly useful as I've never used the basic three classes. The thing that disappointed me was that you unlock threat tracer anyway XD it had it as a special feature of the LE. Get the threat tracer module, I was like awesome, I am so buying the limited edition... then found out everyone gets it anyways XD.

Yes, the phrase "meh" fits my LE experience exactly. In the early days I felt like wearing the shiny dogtag surround pretty much meant "I am one of the dupes that pre-ordered this!".

If the hologram was in fact exclusive, it would have been fun from time to time (without offending like the FY71 -- no one flames about getting duped by the hologram.)

I wish I had the gold dogtag though it looks much better