Yes, however you have to remove all 5 shelves. These are plastic push-in clips.
Yes, this is available in white. Search for W3036-CSW or use the following link: https://www.homedepot.com/p/Hampton-Bay-Courtland-Polar-White-Finish-Laminate-Shaker-Stock-Assembled-Wall-Kitchen-Cabinet-30-in-x-36-in-x-12-in-W3036-CSW/314970836
27" wide base cabinet is available. Please search for B27-CSW or use the following link: https://www.homedepot.com/p/Hampton-Bay-Courtland-Polar-White-Finish-Laminate-Shaker-Stock-Assembled-Base-Kitchen-Cabinet-27-in-x-34-5-in-x-24-in-B27-CSW/314971195
Yes, the drawer works. So, if you use it as a sink base, you will lose the drawer space. Just convert the drawer panel into a fixed panel that will not open (or use clips to attach it to main frame so you can access under sink).