I want to buy a new premiere elements to replace my old one (vrsn 3), can I upgrade it still or is it too old? Or should I still stick to Premiere elements?
Also, will the new premiere pro edit and save changes to avchd files from Panasonic and Canon without losing any quality?
I came across 'provides native support for avchd'; what does it mean? Does it mean that I can edit and save avchd files with out losing quality?
Does it mean that I can edit and save avchd files with out losing quality?
No, it means you can import and edit AVCHD without transcoding it first. You can't go back to AVCHD losslessly, e.g. Premiere Pro does not do smart encoding. Why would you want to do this, though? Typically, you're going to go to some delivery format, like Bluray or DVD, after editing. It's not common practice to go back to the camera format. Any particular reason you want to do this?
For your several questions...
One... download and try the 30-day free trials
Two... read in the user guides
CS5 User Guides - online and PDF (see link in upper right corner at individual pages)
P-Elements 9 http://help.adobe.com/en_US/premiereelements/using/index.html