Always carry a soft lead carpenters pencil while sanding, and immediately mark exposed nails, slight hollows, excessive scratches, holes to be filled, etc. Pencil marks across the floor before the intermediate sanding cuts also show if the entire floor was sanded. To change from coarse to medium to fine grits, do not skip more than one intermediate grit. A sanding disc on the buffer is more aggressive than screening. Use the next finer grit when discing to avoid swirl scratches.
Some strippers contain wax and other chemicals which can interfere with the finish.
Check with the manufacturer. A new pad can aggressively cut too deep and remove stain, producing a lightened area, or remove too much finish and not give adequate finish thickness. It is not always necessary to bleach before using a white stain. The desired white color may be achieved by the stain only. Staining without bleaching is easier and more trouble-free and does not soften the surface of the wood.