It looks like you're new here. If you want to get involved, click one of these buttons!
Yes, every item you can use in some way decays when it is used. Some items decay very fast, some so slow you will not notice it until several weeks, and everything in between. If you look at for example weapons in PE WIkicharts (dedicated to EU), look at the 'decay' column. Decay varies from 0.020 (0.02pecs/shot, next to nothing) to 175pecs/swing (a unique melee wep, thats 1.75PED/swing!):
Some handhelds like flowers, or decorations you can put to your apartment if you buy one, do not decay. Clothes do not decay in combat (but they do when you color/bleach them). There may be some others I have forgotten.
Your character need not to eat/drink/rest. After combat tho you often need to 'rest', ie. wait for the very slow auto-healing, if you don't like to use one of the various first-aid-packs/mindforce healing chips.
You can have pets, and they consume quite a lot food. So far there is not much use for pets though, they for example cannot enter combat with you (I assume it'll be implemented sometime in the future, just guesswork). You can only ask them follow you, and do some simple tricks. This commanding give you some skills of which some are useful in other professions too.