This goes beyond meeting new players, though, for often groups composed of people who played with each other for long had their own unspoken assumption they never spoke of, and which because of various reasons never collided with each other, sometimes for years, until they came into a sudden spotlight causing confusion and misunderstanding.
As I have spoken in the past on some of my gaming lectures: discussion of games is important.
So, to answer the first ten of Owen's questions:
#1. Would you prefer a GM be entirely beholden to the game rules and die rolls, or secretly make changes if it leads to a more interesting, or more dramatic, or more fulfilling game session?
Rules are tool for the GM to help with making the decisions. As every tool, they should be used for benefit of the situation and GM is supposed to decide how much of them should be used, possibly even discarding them when they cause more problems than they solve. It's good to know the actual rules before discarding them, though. Also, sometimes playing a 100% rule-focused game can be fun from time to time.
#2. Give one concrete example of when a GM fudging die rolls or rules might lead to a more interesting, or more dramatic, or more fulfilling game session?
I'd go with a sort of fudging rules here: A GM should not ask for a roll when the rules call for one, if he does not want to have the story derailed by failure, i.e. don't ask the player for roll when you don't intend to play along the failure in the first place. It's better to not ask for the roll than ask for the roll and then try to force success anyway. I done that in the past and it spoils the game.
#3. Does it make a difference to your preference if the GM is entirely open about making changes? What if the GM can hide any change so you never even suspect it?
I am ok with GM making changes, either planned or on the fly. Some changes should be clear and open (i.e. rule changes, major setting changes, anything that connects to the crunch of already created characters and most of things that connect to the fluff of the character). Retconning events that took place on session should be consulted with players, especially when it involves their direct action. E.g. saying that "oh, by the way, I was wrong about introducing the gossip about the war in the North, you haven't heard that" is completely ok, saying "no, you didn't actually win the war in the North, it didn't happen" is not ok unless the players agree to the change OR it is a separate campaign with different characters where the events of the other campaign hadn't happened in the first place.
#4. Do you consider altering NPC attitudes or personalities from their originally planned starting points, or changing the plot of a future game session based on interesting ideas that come up in play, to be GM fudging, or just normal GM activities, or both?
Normal GM activity, though any changes to the NPCs attitudes and personalities after they are introduced should at least try to be consistent and/or explainable. NPCs and plot nature are uncertain until the PCs interact with it in some way (or learn of it in reliable way). Player-introduced ideas for plot elements and directions are often fun, they also tend to be appreciated by players (or at least players I usually play with).
#5. Should a GM be able to veto the color of a PC’s eyes? Or is that none of the GM’s business?
Yes, when the choice goes beyond the normal range for the PC's race without explanation fitting the setting and theme of the game. E.g. if we are playing a modern game that is completely mundane without supernatural or SF elements, the GM can say no to glowing eyes. The GM is responsible for the world's consistency, so don't come back crying when consequences for unusual choice hit you. E.g. aforementioned glowing eyes in Warhammer? You are either a student of magic, or you are a walking kindling as a mutant... I hope you are smart enough (and good at) to pretend you are a student of magic. Though, the GM should warn you before starting that you are asking for trouble or ban a character that would be disruptive to the game or unfun to play in the first place.
GM might insist on restricting certain trait choice when it should be a direct result of the PC's background. E.g. you want to play Robert Baratheon's secret bastard in Saga Of Ice And Fire game? Black hair, unless your mother happened to be Targaryen... Though I'd be wary of that convoluted background, especially as the GM.
#6. Is the GM a player in an RPG session?
Yes, to a degree. "the session should be fun to all the players" definitely apply to GM, though range of the GM's responsibilities and rights is different from other players.
#7. Should the GM roll dice in secret, roll dice in public view, or roll dice with varying secrecy as appropriate to the nature of the roll?
As the situation demands.
#8. Is being the GM a chore, or a privilege?
Being the GM is fun and an obligation.
#9. How much of the success of an RPG session is determined by the quality and actions of the GM? Would you prefer an awesome RPG ruleset with an awesome adventure and awesome other players run by a mediocre GM; or a mediocre RPG ruleset with a mediocre adventure and mediocre other players under an awesome GM?
This one is hard (because of the putting an awesome GM against mediocre players, otherwise the choice would be a no-brainer). Both the mediocre GM and mediocre players can spoil the game. Awesome GM can help overcome mediocre RPG ruleset, and to a certain degree deal with mediocre other players, though its easier to deal with crappy ruleset than certain types of players.
#10. What is your pet peeve about GMs, expressed in a way that makes it generic and impossible to connect to any one specific GM?
GM insisting on PC's actions when no form of actual mind control was involved. Note it does not applies to background story of a one-shot games, or suggestions what happened in the downtime for the character that fit the character (like simple explanations why our Fading Suns characters were on this or that planet at the start of adventure, though later it was us deciding where we go according to events taking place) nor explanations why the PC isn't present when the player couldn't make to the session.
That's it for now. More when Owen puts more of his questions to ponder on.