theBearJewOnly reason why I mention ND's is because my brother has one and too some really good shots with it in the daylight. Said that it tricks the camera into thing its night basically so the light and color is much more sharp. I'm sure I summarized that terribly.
it doesnt trick the camera, optimally you are making all the decisions for the camera as far as exposure (like shooting manually). the point of a nd is to remove light for long exposures. like if you want to take a 10 second exposure of something in bright daylight, you can only lower your iso so much and use a lower aperature while still getting the same effect.
say you want to shoot something at 10 sec exposure and f/5.6 in the middle of the day for any reason, it might still be overexposed even with the lowest iso. a nd filter would be used to remove another however many stops of light you need to get the proper exposure.
putting anything in front of the lens will decrease optical quality. why buy a super nice lens and mess up the pictures with a cheap filter (unless of course you buy a really nice one). if its a shitty lens it really doesnt need to be protected. wait until you see the need for a filter for particular shots, then start getting them
the only exception to this imo is i use a ~$30 polarizing filter when im filming because ive had too much snow sprayed at me and i want to protect the front element of my lens from it, and it helps cut down a slight amount of glare from the snow