1. Looks like a nasturtium flower. 2. Anagallis arvensis. 4. A Brassicaea, perhaps a Cardamine spp.; it would be helpful to see leaves, but chances are, someone will be able to ID it.
For #4, I'm not sure that the flower arrangement really matches Lobularia maritima, sweet alyssum... seems to be more of a raceme than an umbel?
Yes, it is a raceme.... and looks exactly like an Alyssum-flower! :) http://www.dkimages.com/discover/previews/804/95005317.JPG