i can't import songs

Hi,
Wow - So many disgruntled iTunes users. I am feeling the same way today.
Admit I've used an iphone for nearly a year now (4S and now the 5).
It took me a while to figure out the latest iTunes when I scored the i5, but so far I've managed to get a lot of songs onto it.
feels a little more cumbersome perhaps.

anyway, trouble here...

I was *TRYING to add a new song to my phone yesterday.
It's an updated/newer recording of a song my band recorded.

I got the new song I wanted ready to import (it's an mp3), then directly from my phone, I swiped and deleted the old one.
These songs had the same name, but no matter what I do I can't right click the track from my itunes library and send it to my playlist (the actual phone).
I see the track, but there's an exclamation mark. I did some googling and it seems maybe I moved some folders of songs around, so iTunes doesn't remember where to find it.

Previous version of iTunes was so simple. Just drag a song from a Windows window, into iTunes (pointing at my phone) and it would be on the phone!
This latest iTunes seems so horrible and difficult. I spent a good half hour trying all sorts of hacks and reading help pages, still can't put this newest version of the same song on there.

I'm not a MAC user. I know little about Apple apart from using the phone itself (rarely use iTunes unless I HAVE TO).

I'm also too scared to 'sync' my phone with itunes in case i lose stuff I've put on the phone that has since been removed from my computer (mostly songs).
I imported a ton of folders of albums and many have already been moved back to their original folders or now been deleted to save hard drive space.

I'm an apple n00b so I figure I need links to info on basics of adding and removing songs from itunes, and importing/deleting songs from the phone itself.

I have looked at help from inside itunes but there are just pages and pages of info and it's hard to know just what to look up when a lot of these leads from a search don't even answer my question.

Feel like giving up and getting a completely different phone :/