Some people get postcards or emails with discount codes.
Disney also gives codes for people with Annual Passes or Florida Resident Passes or whatever.
I honestly don't know if Disney will look them up for you or not.

The DIS has a page with discounts:
http://www.wdwinfo.com/discounts.html
Upgrades - I'm assuming you're talking the free ones.

Upgrades are usually to a better view or to the Club Level. Just when and how the Disney people give them out is the subject of MUCH discussion around here.
Some people think that if you check in early or late, you're more likely to get them. Others think that if you ask real nice, you'll get one. On an on it goes.
I've received my fair share of upgrades and have received them at all different hours of checking in. I've never asked. I always book what I want - if I get a better view, that's nice - but when I really want a good view, I pay for it.

I couldn't care less about getting bumped to club level and generally prefer not be there, anyway.
They bumped me to club level once and I said I'd rather not be there and they told me that was all they had - I'd have to go to another resort if I didn't take it. So, I get the feeling they *might* sometimes be "upgrading" people because they've nowhere else to put them.
So, that's my $.02 on that.
