Is Tobi shisui

Answer 1

No, if you read the latest manga like on Mangareader.net, you'll see that Kabuto revives Madara and if Tobi was Madara, he should be dead. Tobi is most likely Obito, Kakashi's lost teammate, because Obito gave his left eye to Kakashi and the mask only reveals his right eye. Tobi soon replaces his right eye with the rinnegan which he takes from Nagato's dead body and he kills Konan.

Answer 2

Well It Is Considered That Tobi Is Madara In Obito´s Body But Personally I Think Tobi Is Obito Because Madara Tried To Attack The 4th Hokage Which Was Years Before Obito Was Born. Though Madara Could Have Went To Tobi When His Body Was Crushed And "Swapped" Bodies Like Orichimaru Tried To Do To Sasuke. Or Madara Could Have Died Before Obito´s Body Was Crushed So Maybe Obito Got Out Of The Rubbles That Were Crushing His Bodies And A Few Years Later Joined The Akatsuki. Or If It Was Madara In Obito´s Body That Explains Why He Joined The Akatsuki. Since The Akatsuki´s Leader Was The 4th Hokage (Minato Usumaki/Naruto´s Father) Madara Maybe Was Trying To Attack Him Again. If Madara Sucsided He Would Rule The Akatsuki And Might Have Tried To Attack Konoha. Madara Might Have Created The Akatsuki But Why Would The 4th Hokage Be Leading It? Well After Madara Kind Of "Disappeared" The 4th Hokage Might Have Token Over The Akatsuki. Pein Ussualy Acts Like He´s The Leader Of The Akatsuki But He´s Not. Tobi Joined The Akatsuki When He Found Sasori´s Ring. So Lets Put It This Way: Tobi=Obito+Madara In The Same Body. And That Explains Why Tobi Wears A Mask With Only A Opening Near The Right Eye Since Obito Gave His Left Eye To Kakashi When Kakashi Lost His Left Eye When They Were Trying To Rescue Rin. And That's Why Kakashi Has Sharingan On His Left Eye.

I Might Have Answered More Questions Than You Asked :P

But Hope This Helped!

Answer 3

No. He's Obito.