Thinking of getting an iPod Nano 4th Gen...?

Before I go out and buy one, I am asking of someones help the clarify a few things for me please. I can get this for $155 at a Big W store or my friend may even give me his un-used one if his GF doesn't already use it. Here are the things I wanted to clear up (I have already read reviews):

1.) I previously owned a Samsung YP-U3 while using Sennheiser CX-300 II headphones, which I have now upgraded to the CX-400 II which are awesome, mainly because of the Bass it can handle. The sound quality on my previous mp3 player was what I would consider fantastic, especially because of the 3d-user enhance and 5 level bass boost. How good is the sound quality on the Ipod Nano 4th Gen? Does it have a custom equalizer with bass boost?

2.) How good is the battery (please tell me your personel experience along with how much your used it a day and how often you had to re-charge it).

3.) My previous MP3 player was simple enough to allow me to drag + drop files through windows explorer. I am aware I must use iTunes to add music to the iPod's. My mum already has an iPod Nano that is sync'd with the current iTunes library. How hard is it to learn how to add music via the iTunes library? If I plug in the iPod while it automatically start sync'ing with the iTunes library and adding music I do not want?

4.)What are some cool features of this iPod Nano 4th Gen?

Thanks alot in advanced if you are able to answer some or all of these questions.