Player/GM collaboration?

How much do you talk with the GM about the kind of game you want? Or to your players about the kind of game they want you to run? Do you prefer a "this is my game, take it or leave" approach from the GM, or do you build the whole premise collaboratively from the ground up? Or somewhere in between?

Does the way you handle this issue vary depending on whether you're playing or game-mastering? That is to say, do you prefer a collaborative approach when you're a player even if you're pretty much "take it or leave it" when you GM yourself? Or do you encourage player participation in the premise when you GM, even if you're happy to leave that work to your GM when you play?

Does it matter if you're putting together a brand new group or running for a group you've had for ages? When you're starting a new group, do you decide on the premise and then recruit players for that, or recruit players and then work on a premise together? When you're coming up with a new game for an old group, is it usually built on conversations you've with them over the course of the last game, or are you more likely to pitch them an idea of your own more-or-less cold?

Does system matter?

Does system matter?

Is there one roleplaying system that you prefer to play above all others? Are there systems that you absolutely won't play? Do social considerations override those preferences? Would you rather play with the right people, or the right system? Or are the right people the ones playing the right system?

Would you rather play something familiar, or try something new? Are you still playing the first system you started gaming with? When you try a new system, would you rather that it be similar to one you know, or something crazy and different? Or are there certain features that you know and love, and others you don't mind if the system experiments with?

Would you rather play the perfect system, or one that's not quite perfect but you know inside and out? Are there systems that you originally hated, but fell in love with when you mastered them? What about the other way around? Any system that you used to love, but now don't remember well enough to use properly?

Teaching D&D

If you happen to be an experienced DM, and you're teaching D&D to someone, is it best to go with Players Handbook only, dungeon crawling, vaguely Greyhawk-ian standard D&D? Is it okay to add in more diverse mechanical material? More diverse thematic material? What if your normal game doesn't fall into any of those categories?

On setting--better to go with a published setting, or homebrew? Does it matter? Does it make a difference how weird the setting is? Is something like Eberron or Dark Sun, which both change various baseline assumptions about the world and how the game's played, better if its an established setting, so new players have a place to go to get a more solid grounding in it?

What if you really want to play something like Arcana Evolved, or Iron Heroes, but the only players around are new? Better to start them off with the basics, or is it okay to start them with the slightly off-beat stuff? In some ways, Iron Heroes might be easier to learn--none of that magic stuff to deal with. But how would learning it first change a player's perception of D&D?

What if you've got a mixed group? Some new, some old? Should you get the older players on board with staying core, to keep the group simpler for the new players? Should you let the experienced players use wacky supplements, but tell the new players to keep to the basics? Will new players even notice?

On new stuff--does it make a difference, in both whether to use it at all and who to allow to use it, whether it's new variations on old stuff or entirely new things? New feats and spells? New races? New prestige classes? New base classes? New subsystems? Are there some subsystems that are easier to use with new players than others? Psionics? Incarnum? Book of Nine Swords?

How much weird stuff should a DM use, when running a game for new players? Should you stay core, too? Take advantage of having some players who don't necessarily know that a troll has fire resistance? Or is it okay to go weird, since your players don't know the difference and aren't keep track of it? Is it okay to use PC parts in your NPCs that you aren't allowing the players to use? Is it okay to use subsystems that you aren't allowing your players to use? (Those last two don't apply just to new player campaigns.)

Learning D&D

Is it better to learn D&D (or any roleplaying game) from an experienced DM, or a brand new one? With a group of entirely new players, or a group where everyone but one or two people basically knows what's going on?

Is it better to learn to DM as your first D&D experience, or after you've been playing it for a while? With brand new players, or experienced players? Is it possible to learn to play D&D as the DM, but with experienced players?

By better I mean--which is more fun? Which is more likely to keep you in the hobby for the long run? Does it affect playing style? DMing style? DMing skill?

How do most people learn to play D&D? Are there differences between how D&D is learned, and how other games are learned?

What effect does already knowing another game have on the learning process? Does it have any other, longterm effects?

Probably some of these questions are answered by market research. I know that Wizards published a study of the player population and its various habits in the run-up to 3rd Edition. I assume they still do market research; do they still publish it? Do they have plans to publish it?