MY FIRST GAME DRAFT

If you're going for an MMO feel, then I recommend 8-directional movement scripts. They are available for all versions of RPG Maker. I also recommend time of day/weather scripts, also available for all makers, and doable with built-in events and functions. Same goes for the monthly events (the time script can do those). I like seeing games that use social and time-based aspects, as they give so much more to do than just "Fight. Story scene. Shop. Fight. Boss. Story. End." You could easily do a relationship system using variables and switches, and I think some scripts exist for really complex dating-sim style relations. So good luck with the story and preparation, and hopefully you'll have more to show about your project as you get closer to the purchase of the maker, and can start taking some more ideas from the community.

author=Kadamode
So let's say the main mechanics would be making a group, pit that group against another group and let the RNG decide the outcome. What if you don't have a group? What if you're alone? At least I could focus more on the socializing element when it comes to making a guild. The only viable option that I can think of for now is a separate 1-on-1 fights for duels and such, which I don't really like. So maybe I can use the same mechanics except limit it to 1 on both sides, which seems weird or make a different battle mechanic for 1 on 1 fights which seems weirder. Any suggestions?

Besides all that I've mentioned, are there any other ways to conquer an MMORPG server besides being the best guild, the richest merchant and the deadliest solo player? I think I would like to have 5 different endings rather than 3.

Well if you're using an RNG for the outcome of battles, you could have guild/party size as a variable that will be added to or used as a multiplier for the RNG, with a larger guild and higher level characters increasing your odds of winning. A solo player is unlikely to beat a large guild alone, unless their level is high. Likewise, a guild with a dozen low-level members wouldn't be able to conquer a trio whose level is much higher than theirs, unless the massive number of members somehow overpowers the trio. If you're going to be randomly generating guilds, this could lead to issue where the game makes an absurdly large guild to take on a strong player, unless you impose limits. I'm not quite sure where you're going with the battle concept, but I might just be reading it wrong.

As for the endings, you could have a bachelor/bachelorette ending, where you are the player with the most lovers in the game. This would really make heavy use of any social functions you put into the game. You could also just have a retirement ending, where you settle down and have a family (if you end up implementing marriage, then this would be like an 'easy' ending). Some other more abstract ideas would be a Craftsman/Collector ending, where you either craft or possess every item available, or a monster hunter ending where you've killed every monster in the game (if you add any non-human/non-guild battles), or a City-Builder function where you can buy land and upgrade it to a city, and when big or populated enough, it becomes the new capital and you win with a Political ending. Most of these would be hard to implement, but if you were planning on adding the necessary features anyway, such as crafting, then it might be worth a shot.

There's actually a built-in event command called "Show Choices" that opens a box where the player chooses from a few options. I don't remember the limit of choices, but you can just have a Page Two of choices, or find/make a script that expands the number of choices if the default isn't enough. Just have the choice menu pop up when the player leaves town.

As for the city/castle builder, the easiest way to do it in RPG Maker is to have a place where the player invests money, and at certain amounts, the city/castle gets bigger. For an actual build-your-own type of thing, I wouldn't know where to begin.

Edit: Similar to The Elder Scrolls IV: Oblivion castles & houses, where you chose what to add to your house from a merchant menu, and then it was added in a predetermined location.

In related news, VX Ace is on sale on Amazon for both the digital version and the physical version. That should lessen the blow to OP's paycheck.