This may be a dunce's questions but I'd appreciate any help...

I've got 900 photos on my Nexus One and just synced/uploaded them to my drop box on Picasa Web.

How can I tell whether I can now delete them from my phone to free up some space. I'm totally paranoid that I will delete them from my phone and they will also disappear from Picasa web too.

I assume there may be a difference between uploading pics and and syncing them - the latter sounds like there is ongoing communication between the two which may mean they will delete?

I used the Picasa app on my phone to do the sharing/uploading but it is now in the middle of the process (only 500 pics left to go at present!!!) so I don't want to touch it until it's finished. Therefore I can't check on the wording at the moment about whether it was an upload or sync.

Also, if the general consensus is I can delete - how do I do that in one go?

Thank you