Greetings! Welcome to SotE!
To answer some of your questions yes psionics are allowed, and if you want to brainstorm the Plotting Center is a good place to start. There are a few different plots going on right now, but the nice thing about SotE is that there is no "main" plot and players are free to run their own plots as long as it isn't doesn't have too much of an impact on the overall setting (you would need permission for that). Also you are more than welcome to make a dragon rider outside of Adela if you want. Just remember that they would be rarer, and more likely to draw attention from others.
Anyway, I hope you enjoy it here, and if you have anymore questions don't hesitate to ask someone. ^^