All of your questions are answered in the documentation link you've provided. But to break them down.
A) Whats the differnece between '*image values' and 'image labels'
Image Values contain the path to the image. Example: http://website.com/path/to/image.jpg
Image Labels are the text descriptions assigned to the images. Example: Blue Shirt
B) All I have a productsFeed.csv file what image columns should keep in it..?
Your CSV should contain all the image columns you want to upload to Magento.
C) Does Magmi can able to download remote Images from URL? sinc ein my csv i have all remote images
Yes, as stated in the documentation.
Image Processor accepts URL as valid image location for any type of image (standard or extra) Image processor will download the remote images & put them in the appropriate directory for magento usage.