Yes it does, unless your barrel is stamped .223 .
It should be marked on the barrel.
as long as there are no cracks in the barrel, yes. it simply means not to shoot slugs thru the barrel.
No. Only what is stamped on the barrel.
Have it checked out by a competent gun smith.
A Marlin model 60 should only be shot with 22 long rifle ammunition. It should be marked on the barrel or receiver and may say 22LR.
DO NOT ATTEMPT TO FIRE MODERN AMMUNITION until a good gunsmith checks it out.
Have a gunsmith check the gun before you fire it.
The sizes of shells it accepts will be stamped on the barrel
NO THE AMMUNITION MUST MATCH EXACTLY WHAT IS STAMPED ON THE BARREL. THIS IS AN ACCIDENT WAITING TO HAPPEN. If you dont know take the gun to a gunsmith and have him check this for you. Not Walmart.
It should fire until the water gets inside the ammunition and degrades the gun powder. If the ammunition is well sealed against moisture then it will shoot until the barrel clogs or the action rusts.