1. How to maintain an RPG.
Come online often and take care of all your NPCs (Non Playable Characters) - bring all the players together, but don't 'force it', give opportunities. They want to get together too, but they need a plot reason to do so.
2. How to start it.
Write out a general idea of the story, some plot device that acts as the motive for players to act. Then Create the villians and NPCs, with NPCs that you control being as important as your bosses. Make your villians dynamic though, we're an anime forum, so we love various twists, like seemingly good NPCs turning out to be the villains, anti-villians and villains that turn good. You can do these little twists with things other then the villains as well - if you know one of the players, you could even secretly work out that they're a villain!
3. How to end it.
Sadly. More then likely the RP will just die... That's the nature of RPs on here. However, if you format it, you can have it end in a variety of manners. You can set a time-table after which the world ends (but realize it will probably end with everyone dead). Get your players through at any cost and then wrap it up by giving it an ending paragraph (you can always start another RP with the same characters later) - or if you're evil, place victory conditions in the game and if they fail cause a game over to trigger. Do put a lot of work into the game over though, also this can always lead into another RP. As long as it was fun, it's makes for an interesting plot element - but if you god-mod, you'll end up causing players to quit.
4. How to work the characters into the story.
Other then NPCs, that's the job of the players to do. They create their own characters, you create police officers, mayors, dojo masters, teachers and what not that give the characters crucial bits of advice, training or simply develop their characters. You get to control a ton of characters, but your job can get kind of boring on the regular NPCs occasionally.
5. How to create "boss battles". (Villains)
With DICE - or just have them write it out and eventually have the boss give it up and run or surrender or such (there are plenty of plot-ways to do this). Don't just do battles for battles sake though, make it important to the plot. (also figure out a system for if the players attack each other - we have a lot of schemer RPers on here who vie for global domination and don't mind taking unique routes to achieve their ends). Also, make your villains fun and interesting - give them a reason to want to know about this character more even if they hate him.
6. What attracts the most players.
It's a mystery. If you figure it out, let me know.
7. Best "Battle System". (How the characters fight opponents and each other, and how to decide who wins)
The players on CAA like 'light-RPing'. So the less rules the less dice rolls the better. Go for just having them write out their battles and just work with them to let them get a victory. Peanut and I have tried complicated - I had an entire massive spreadsheet with mile-long equations that calculated battle parameters and Peanut worked with something quite a bit more simple. Players didn't like either and it made updates incredibly difficult for us as GMs (as we sometimes had to do hundreds of calculations to figure out what happened). Focus on the story and don't sweat the small stuff - save the harder thought out stuff for the 'Big' boss battles.
8. How long does a normal RPG last?
Anywheres from a week to several years. If it goes on for several years - consider it a major victory.Typically, even if it dies, it will have enough steam to attract the old and some new players the next time around.
EDIT: Also if you want to go really crazy you can find PDF books on the subject. I've yet to use it (I'm sure it will be awesome if I do) but I have OVA for instance. It goes into detail on this question for a specific system in about over a 100 pages. But this has nothing on the tomes for D&D for instance. However, I'm not that crazy and the larger ones tend to limit you more.
Walk in, introduce yourself, create a character you'd like to play as (most RPGs on here require minimum stats that simply give other players an idea what your character looks like and gives you an idea about their personality and history) and then write stories for them and them alone in the RP. When other players or things interact with you, either by other players or by GM, then interact back as you expect your character would. That's called 'getting in character'. Most of all, just have fun writing for your character and reading what other players write. RPGs are like free books written by you and a group of friends, like an interactive choose your own adventure that's multi-player and the choices are infinite. To be a really good RP player, learn to be a really good author.
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