If you have done a backup, then do another backup several months later - can you restore from both backups, or does a newer backup delete the previous backup? ( I want to retreive @200 pix from an earlier backup w/o loosing the 60 newer pix on my iPhone)

There is only one backup in that situation. The backup created or updated several months prior will be updated.

If the 200 pix included with the original backup have not been deleted from the iPhone's Camera Roll, the 60 newer pix will be added to the original backup since the original backup will be updated.

Photos/videos in the Camera Roll can and should be imported by your computer as with any other digital camera. Not a good idea to depend on the iPhone's backup alone for this data. The iPhone's backup includes a significant amount of other data besides photos in the Camera Roll.

http://support.apple.com/kb/HT4083