How large will the map be?
Will it be a world like in WoW where you can run around freely without restrictions or will it be more of a strategic map where you chose where to deploy?

My preference would be a large world that you could walk around freely, ride around on your Bike or Thunderwolf, drive or be driven around in a Rhino, order a pickup by a Thunderhawk to be drooped of anywhere you have air superiority or try to penetrate enemy air defense and be shot down and crash, or just return with the Thunderhawk to your battle barge and redeploy by deepstriking far into enemy territory with drop pods.

The devs said it will be a large map, around 400km across I think. One map for one continent.

I doubt it's going to be quite that big, simply due to technical constraints. It would be awesome, but I don't think we have the hardware for a 16,000 km2 (400x400) map.

Based on how they've described travel times, I'd estimate anywhere between 6x6km to 12x12km (36km2 and 144km2 respectively).

I do not remember anything being said about size other than that its is supposed to be an open world. Over in the FAQs they have said that there will be multiple servers and that more will operate in the zones that have more player action.
I honestly never got into WoW or anything, but I remember how Tom Clancys Endwar (think that was the name) worked. Considering that there are almost 20,000 in the forum at this point we should expect a pretty decent size that can handle the weekend traffic with ease. I cannot remember where it was mentioned but they said the play style should be able to handle some immense battle forces. This combined with the multiple zones should be good right?!
And there is also the open world due to the side quests you can do. I expect very limited boundries.

the exact dev citation is "400km2" and you need "one hour for traversing" and is "one of the smallest map"

Ah, that makes more sense. 400km2 is 20 x 20, which is still pretty huge but sounds technically feasible.

Sweet. This makes me happy. Especially the "one of the smallest maps" part. I want to be able to get lost in this game and lose all track of time! Is it 2015 yet?

Sadly not! But time flows different in the Warp.

But to the topic, it will be 1 Sever, with multiple "Maps", some are "only" 400km². Other might be much bigger

This is from the FAQ:

i hadn't read that yet. i very much hope that this is the case.

if they're going to advertise that players will provide the content, this gives the players the possibility to do so