My cr-1 was a completely done with as well before we even heard from the K3!! All I did was send Mtl an email stating I already had my CR-1 visa, thus no requirement for the K3. They replied back thanking me for letting them know, thus not having to worry about it!!!
On ur greencard it will have an expiration date(CR-1 is good for 2 yrs)! 90 days prior to that you will send in the I-751 and its requirements
http://www.uscis.gov/files/form/I-751.pdf plus lots of info on here
http://www.visajourney.com/forums/index.php?showforum=86Very easy form to fill out. Just remember you can mail in the form I-751 anytime within that 90 day window, which is based on the expiration date on ur greencard, IT has nothing to do with ur wedding anniversary!! This new greencard is now good for 10 yrs!
Your greencard is to be in your possession at all times,not locked up!! Do I carry mine with me all the time? For the most part yes (if my wallet goes with me, its there!!) If I go for a run, no! lol