Thank you for your Whitehaus Purchase. Whitehaus understands that this toilet is not your normal install. That is the reasons for the install video that is on Home Depot's website and the Whitehaus website. Please note that step 2 on the install instructions shows you exactly how to measure for the plastic guides. You need to make sure that you know the model number of your toilet. In your case you purchased the WHMFL3351-EB and your measurements are shown in the guide box at the bottom left as a 3351-EB L= 5 1/8" M=8 5/8". You would then make your measurements off the center line where the drainage outlet (Flange) is located. Simply follow the guide.
As for the toilet seat, obviously a normal bathroom cleaner will work fine. Installing the seat is a breeze. Simply put the brackets into the pre-drilled holes where the seat is supposed to be installed. Then put the seat with the screws over the bracket and tighten the screws into bracket. Pretty simple!