Diablo III revised casting call.

[Ruvanal]

As such these characters will be locked in. All items used will be stuff that we find during the playthough, and commentary related to story/game events will be presented as if this were our first playthrough. That doesn't mean players should play dumb just that, in the microcosm of the LP, it should be played as if spoiler-free.

Yes the player count in a game instance is limited to four. Also as of the last time I checked a couple weeks ago, it was only possible to control the players in a game group by doing private games and invites to players on your friends list. That required inviting through direct meeting in open games, RealID or the new (and buggy right now) BattleTag IDs.

Crafting of gear can be very important to getting some quality gear as you play. The gear that I have been able to craft usually has be a magnitude or more greater than anything I could find. Access the smith crafter (and any others later in the game) is on an account basis so once he is opened on any character, at least part of his services will be available to even a fresh made level 1. What the smith can craft for you is up graded as you level him up with gold purchases. Higher smith levels also need crafting mats and I also hear that there will be some sort of plans that drop for increasing his repertoire.

Your stash is an account wide stash that makes it easy to shift items and crafting mats to other toons. It is increased in size with gold purchases. Any gold you earn on a character is available to all toons on that account.

So plan now a little on what you mean by "All items used will be stuff that we find during the play though" as it will not necessarily be easy to keep these aspects listed above from affecting your play through.