Certainly not the only one, and this isn't a bad idea for a thread at all.
Check the first post
In This Sticky Thread. While it has not been updated 2003, it's still incredibly applicable.
As for how much time you spend in a game, well, that depends how fast the games you join move, how much time you want to devote, and how many games you're a part of. If you're involved in 5+ games, expect to have posts to reply to almost every day. But if you're only in 1 game, the pace can be about a post a day if not slower. It all depends upon the GM and the players in question, and you can devote as much or as little to the game as you'd like (although I'd always recommend at least not posting less than a paragraph, unless you only need 1 sentence to move the action).
For a first timer, look at the topics that are Recruitment threads in Talking The Talk: these are GMs looking for players for games. The first post will usually outline what type of game and system, as well as what they're looking for in regards to players and characters. From there, just get talking with the folks in those threads, build a character according to the guidelines, and get to know your new party members.
Most people here are going to use
Coyote Code to do their rolls, which I have found is very serviceable.
I'd also advise you to get a little familiar with some of the coding here, like putting things into statblocks
[sblock=Like This]This can be really useful for not cluttering your posts with your character stats or rolls and actions[/sblock]
Just quote my post to see the source code there.
Likewise, differentiating your speech with
a flash of color here and there can be very useful for highlighting your Dialog, and is often a good practice to get into so you're not just giving a wall of black and white text to read. You can even get fancier and
use Italics to show Internal Thought, or use
Bold to highlight very important parts of your post, but also try not to get carried away with stylistic choices that can be distracting in your post: remember, you're writing to be read and understood, first and foremost.
Honestly, the sticky I linked to is a great rundown, and I'd start there. Any other questions, please feel free to ask, and welcome to the boards, EnWorlder!