If i delete pictures from my camera roll on my iPhone will they be deleted from my iCloud also?

They won't be deleted from photo stream if that's what you mean. But if you want to keep these photos, import them to your computer from the camera roll before deleting them, as explained here: http://support.apple.com/kb/HT4083. The reason for this is because photo stream photos only remain in iCloud for 30 days. If you ever disconnect from your photo stream, when you re-enable it you will lose any photos old than 30 days so your can use photo stream as a backup. Also, photo stream photos on your iOS device are lower resolution than the original photos in your camera roll.

I'm assuming you are not talking about the Photo Stream service.

If that's right, your photos are not being synced to icloud, except as part of a backup if you have that turned on. Always sync photos to a computer for archiving, icloud is basically for syncing photos (photo stream) to other devices. Yes, the backup can be used to restore photos from camera roll only, but that involves deleting everything from your device first.

Photo stream is something else, it's a syncing service. Photos stay on the servers for up to 30 days, so it's not a long term storage service. If you delete photos from the photo stream group, that deletes it from the stream's servers.