Yes, he still retains a significant stake in Bain. However, he has not released the exact details of his actual stake, and, as his released tax filings are quite vague, it is impossible to know much more than the aforementioned generality.
Should he be elected President, he would almost certainly hand his entire financial portfolio over to a wealth management company in the form of a blind trust (as all current Presidents do), so that they could manage his finances WITHOUT him knowing the details of what was sold or traded, so as to avoid a conflict-of-interest when making decisions as President. Though many Presidential candidates do such a handover about now (i.e. when it becomes obvious that they will win their party's nomination), Romney given no indications of such a move. Do note, that this is not required at this point, however.
NO he was not
Mitt Romney is still alive.
Mitt Romney did not own Staples, but he was involved in its founding through his work with Bain Capital, a private equity firm. Bain Capital invested in Staples in the early 1990s, helping to grow the company significantly. Romney's role in the firm contributed to his reputation as a successful businessman, but he was not a direct owner of Staples.
Mitt Romney's birth name is Willard Mitt Romney.
Mitt Romney
Mitt Romney's full name is Willard Mitt Romney.
Mitt Romney's whole name is Willard Mitt Romney.
No Mitt Romney has never been registered as a democrat.
No, Mitt Romney is not gay.
Mitt Romney is 6'2".
Mitt Romney is American.
Mitt Romney is a Mormon