How does the online co-op campaign work?

I know that only a handful of decent games on the PS3 offer an online cooperative campaign/story mode, but there a few games in my backlog that I've yet to play ... that offer this.

And I'm confused as to how exactly it will work. Does the system/network automatically assign you to other people on PSN, or can you only play with people on your friend list?

Also, for instance in Resistance 2, you can have up to eight players participating in the online co-op campaign ... but does this mean you have to go through the entire thingwith the same SEVEN people the entire time? Or does your team "change" every time you enter a new stage or level? I've read that you can "drop-in" or "drop-out" at any time, what exactly does this refer to? I just want to be able to play through the co-op story, but not have to work around other people's schedules and stuff in order to do so.

Resident Evil 4 is another game that seems to offer an online co-op campaign. But I've heard that this one is actually the SAME as the offline story mode, except you can opt to play it online. Well, does this mean that if you start a game online, you can't continue offline? And vice versa?

Finally, a game that a lot of people are probably playing right now, LittleBigPlanet (and what I'm about to venture into), actually requires at least two players in almost every single stage (if you want to get all of the trophies for collecting all the item bubbles). What I'm really confused about is whether or not you can do this ONLINE. I know that you can play with up to four people online, but is this the actual story/campaign mode of the game, and would you be able to get item bubbles (and the trophies) this way? If so, then I would prefer to paly the entire game online with three other people, instead of going through the whole thing offline by myself, and then having to do it all again in order to collect everything.

Resistance 2 - You can play the whole co-op campaign with different people, not just the ones on your friend's list. What "drop-in/drop-out" means is that you are free to drop-in (join) a mission that a host has chosen, then if you want to leave your current team for whatever reason, you can simply drop-out of the game you are currently in and join a new one.

I'm guessing you meant RE5, not 4, right? If so, regardless if you start the story mode online or offline, you should be able to continue with the story where you left off, as long as you were the person that HOSTED the co-op.

LBP - Yes, you can play through the actual story mode online. And yes, you can get all the item bubbles through online.

Hope that made sense. :P (Its 6 AM and I'm not fully awake yet, so if something I said confuses you, then feel free to point it out and I'll try and clarify it a little better.

For Resistance 2 co op, you have the option of pressing "Play" and it will put you into a game that is about to start. In the game lobby you will see the list of other players that you will be playing with - random peeps that also pressed Play and the game itself will put you into a random mission level (Orick, Chicago, etc.). If you press "Find Game" then you will be taken to a screen that lists the current missions that people are hosting and from there you can choose what mission level you want to play.

You will be playing with the same people on each mission until they/you drop out. You can play with your friends by creating a party first and then where ever you navigate to, your party will automatically follow.

The thing about Resistance 2 co op is that when you choose your mission level, you play that same mission over and over again until you drop out and choose a different one. It doesn't progress to the next mission level once you have completed one successfully. It's kind of wonky, but helpful if you are going after the trophy for collecting intel.

* I had to edit to say: The Co op and MP game play is NOT the same as the SP - it's not like you are going through the SP storyline with online people - it's just specific missions that have some of the same locations as the SP did.

Thanks a lot for the replies, it's exactly as I had hoped the online co-op would be for all three games!

And yes, that was a typo, I did mean to put Resident Evil 5.

Gonna try to platinum LBP ... it seems daunting, but there a lot tougher platinums out there. Should be much easier though if I can team up with random users when I need to complete a stage instead of having to wait for a specific PSN user on my friend list to be ready to tackle that level at the same time I am.

I'm just surprised that, even with 70 million PSN users, there are enough people wanting to play a SPECIFIC stage of Resistance 2 at the exact same time that you want to do so. Regardless, the trophies are the incentive for me to do the online co-op.

I'm still unsure about Resident Evil 5's ability to play through the story offline or online (switching between the two). How would that impact your inventory if you play with a stranger who has different weapons/items each time? And wouldn't people be fighting over which character they could control (I would guess more people would want to be Chris Redfield).

Good luck with getting the plat on LBP. I never got it because of the trophies that required you to create a level and get a certain amount of people to play/like themksire_68

Well, there is an easy (albeit cheap) way that you can try if you still want to get it.

Simply create and upload a very short, basic level ... then use another user account and sign in with a SECOND PSN account (you might need to make a new one if you don't have two, or borrow someone else's). Then you can simply play/heart/tag your own level repeatedly from that second PSN account.

It should take you significantly less time than the gold trophy that requires you to play 150 community levels.