Quick gameplay question

Greetings,

I have been looking into starting up Guildwars with some friends. There are 4 of us total and due to time zone differences, we will realistically only be able to play 2-6 hours a week. I am hoping to play this game excluively with 4 people (missions, quests etc) is that possible? Or are there sections where a large # of people is required? (ala FFXI Dynamis or WoW Raid events)

Thanks for your time.

Well there are henchmen npcs you can use to bolster the ranks.

The maximum party size is 8, (12 in some certain elite mission, 4 then 6 in the early part of the game). You can fill up the free slots with AI henchmen or AI heroes (if you have Nightfall).

I see, I remember reading about the heroes/npcs and the like. That sounds awesome. Thanks for the info.