Yes, you can totally replace the air filter yourself. I replaced mine not too long ago. If it's dirty it will have a brownish/grayish tinge to it, and LOOK dirty. The brand-new air filter looked yellowish to begin with.
As for the hole, I wouldn't worry too much about that either; the guy at Jiffy Lube broke off the tabs holding my air filter lid on and my car still runs fine despite there not being a very good seal. Stupid Jiffy Lube guy.
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If I am not better, at least I am different. --Jean-Jacques Rousseau
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