We haven't installed a toilet yet; could we put the flooring under the toilet? Also, this is going to run up to a PVC shower base; that should be siliconed, right?

Hello Bill and thanks for your inquiry. Yes, the Style Selections Luxury Vinyl Plank should always be installed under the toilet and around the flange, leaving at least 1/4" expansion. We would definitely recommend using a silicone sealant around the toilet flange and also around the perimeter of the bathroom, keeping a 1/4" expansion space around the perimeter of the room and also in front of the tub/shower surround as well. This can either be covered with a quarter round, or a colored sealant can be installed in the expansion space to match the floor. For more information regarding installation, we suggest reviewing the Installation Instructions (found in each carton or on the product page of Lowe's website). Thanks again for choosing Style Selections Luxury Vinyl Plank Flooring and best of luck with your flooring project.