Regarding borrowing from the interest-based bank in order to finance the commercial project, the principle is that it is not permissible except in the case of necessity that permits the prohibitions.

Allah glory be to Him, the most high, says: But if one is forced by necessity, without willful disobedience, nor transgressing due limits,- then he is guiltless. For Allah is Oft-forgiving Most Merciful. Qur’ān 2:173. 

 Necessity is when a person has reached the point of considering losing himself, his productivity (or honor) or part of his body.