Mystic Form is Stronger than SSJ2. Mystic Gohan was More Powerful than SSJ2 Goku or Vegeta during fight with Buu, But Buu after absorbing Gotenks(SSJ3) became stronger than Gohan. Thus, Mystic form more powerful than SSJ2 but less than SSJ3. Kid Buu was way much powerfull than of its any other form.
Mystic Gohan is stronger than Gotenks SSJ 3. Mystic Gohan is not as Strong as SSJ3 Goku. However having said that, Mystic Gohan can definitely last longer in a fight than SSJ3 because that state consumes too much stamina.
Gohan cannot go Super Saiyan after getting Mystic/Ultimate form (though it's not even really a form as much as a full power). First things first, Elder Kai tells Gohan nothing more than to go Super Saiyan, when Gohan attempts to go Super Saiyan with no further instruction, Super Saiyan doesn't happen.
No, they are not at the same level. If you'll recall from the Dragon Ball Z era, Ultimate Gohan was a bit stronger than Super Saiyan 3 Goku.
Ultimate Gohan is very strong. He is stronger than Evil Majin Boo (Buu) also known as Super Boo, and is also stronger than Super Saiyan 3 Goku, Demon Prince Vegeta (Majin Vegeta), and is even stronger than Super Saiyan 3 Gotenks. He is suddenly outclassed when Super Boo absorbed Piccolo and Gotenks.
As no one wants to romantically entangle themselves with the snake Sannin, his son was created as a clone. Except, Mitsuki isn't exactly a full clone. Orochimaru experimented, spliced, and scrambled his genetics to make them as perfect as possible. Best put, Mitsuki is an artificial being.
Orochimaru is a man. He is always addressed as male, always refers to himself as male, has male anatomy, is listed as male in all sources, etc. etc.