Yes.

Lol, well, technically all those things are options. If you post in the Crossroads, you should have some kind of in-character introduction, usually involving the approved character(s) you are using. You should have an out-of-character note explaining the conditions of your RP, the number of people allowed to join, how many characters per RPer, etc. In this case, they usually "sign-up" by writing an post in response with the character(s) they will be using.

Or, you could post a discussion thread in the Dome proposing your RP idea and conditions and allow for people to sign-up out-of-character there.

Both have their advantages and disadvantages, but basically you can do those two things.Depends, your character could try to make a move on their character, BUT you are never allowed to write the other RPer's character's response to your character's attempt. We call that powerplaying here, and it is against the rules to writer another person's character for them without their express permission. Basically, always allow for the other writer to write their character's response, give them a chance to react and respond.

That is the more spontaneous way to do it. Which is fun if you keep an open mind to it. Imagine the drama of unrequited love! (If it turns out their character just isn't interested in yours that way.)

Or you could PM them and ask them what they think. Usually, if your character is having romantic thoughts and feelings of attraction to another person's character it will usually start showing through your own posts as you write your character's thoughts, and they might respond on their own with their character.

Asking never hurts either though.