Any reason these can’t be used as an interior entry... say to a bedroom. In our case, I need a stylish way to go from the garage to my very small living room

Just keep in mind that the door swings in Only One Direction but other than that, it will work fine.   Might want to consider leaving off the bottom and top tracks during the install.   

58-59 1/2 width, Is it possible to order with the fixed panel on the right, and the hinge pivot on the center mullion. Or fixed panel on right side, hinged door on left, pivot left side. On each configuration what would be the width dimension of the hinged door?

Thank you for your question.   In short, it's all the same.  The shower door is reversible so it can be hinged on either side by cartwheeling it 180 degrees.     Additionally, the door and panel placement is interchangeable as well.  The shower door can be on the left with the fixed panel portion on the right and vice-versa, its all the same parts.  

Regarding the size of the door, the swing size is approximately 30 in.   

Thanks so much for shopping at divided.STYLE