Simple questions

Tire guards? Do you mean tire covers? If that's what your asking about, then take a tape measure and measure the tires diameter and pick the size that is equal to or larger than that measurement.
How much sewer hose? Depends. I normally have a 10 foot and a 20 foot piece on board with the appropriate connectors to put them together. I have used all of it more than once. Right now, I am adding another 15 foot piece because the place we will be at next month the storage tank is a ways and down hill from our site. If you have two dump locations then you will also want a "Y" connector and probably two 5 foot hoses in addition to the longer hoses to get to the sewer dump.

Mine has a sewer connection and valve at the rear for the kitchen sink grey water tank. I use a cap with a garden hose fitting and run a 25ft garden hose (color is black)from the sewer cap to the campsite sewer hookup. I have a second garden hose for distance.

The other sewer connection is middle of the 5th wheel for the black and grey tanks for the bathroom. I have two 20 ft sewer hoses in case I need distance.
On the end of the sewer hose I have a fitting which goes into the campsite sewer hookup and it also has a garden hose connection for the hose from the kitchen grey tank.

Simple setup with flexibility.