Please pre-wash any fleece at least a couple of times with a softener-free detergent before use, so the surface is no longer sealed and your piggies are not sitting in their own pee. Never use softener with fleece! You also have to be careful not overload the washing machine - otherwise, the fleece will come out stinking if the ratio of fabric and washing water is not right. Please also wash your fleece regularly at a higher temperature (60 - 90 C) to kill off any bacteria and fungal spores that can build up. This is even more important in a warmer climate! Fleece shrinks more when you wash it at a high temperature, so leave some generous margins at first.
Anti-pil or polar fleece are the best for bedding. I use anti-pil for my own set-up and order it from an online fabric store by the metre. It should last you for several years!
You will have to find out what works best for you in the way of underlay. There is no ideal solution - it pays to use what is easily available to you!