1. if i backup something in timecapsule and delete it from my desktop will it be deleted from the time capsule also?
Yes, sooner or later. Time Machine backs up the changes on your Mac, so if you delete a file from your Mac, Time Machine will back up that change.......and you do not know when this might occur.
If there is plenty of free space on the Time Capsule, the file may not be deleted for some time.
2.every time the timecapsule automatically backsup do all the files once again be saved or only the new files be saved?
Time Machine backs up everything on your Mac during the very first backup, then after that, only the changes that occur on your Mac are backed up.