Front crud catchers stop mud that flies up and into your face. Those neoprene things that go between the fork brace and crown stop the mud that flies forward and up in front of you. When travling at speed you catch this mud back up as it slows and it all ends up in your face.
As for frame protection patches, it's much cheaper to buy a role of helitape and make you own. That way you can make them as big or small and whatever shape you like. Just search on ebay for helitape, helicopter tape or bike protection tape. You will be able to get a 1 meter x 25mm roll for less than you would pay for 5 small lizard skin patches (which have stupid lizards printed on them).
http://www.ebay.co.uk/itm/Helicopter-Bi ... 53dda26fa7
Chainstay protectors: You could use the helitape (two layers maybe) or get a purpose made stick on one or a neoprene velcro on one. Up to you really. The neoprene ones will offer the best protection and can easily be removed for cleaning. If your a bit lazy and its going to get soaking wet and then left on a steel bike to dry in the shed during the winter then maybe a stick on one would be better bet.
http://www.chainreactioncycles.com/Mode ... elID=27985
Some of them come in different sizes as some bike have massive stays and some dont. The one in the link looks like it will fit a typical hardtail.