Does Database Viewer Plus transfer complete database each time?

No, Software trasnfer only changed records like new/updated/deleted records, not complete database each time.

Is my database secured?

Yes, Data transfer between iPhone side DBViewer Plus and Server application is secured as 128 bit AES is used for encryption.

How to get UDID of iphone?

To get Device ID, connect your device to your Mac/PC and launch iTunes. In iTunes, select your device in the ‘Devices’ section and navigate to the Summary tab. Click on the Serial Number label to reveal the Identifier field and the 40 character UDID. Press Ctrl+C to copy the UDID to your clipboard, and paste it in Device ID and Confirm Device ID field.

Whenever I add/edit/delete record on iphone, in Record view I get Red/Cyan color.

Cyan color indicates that record synchronization is still in progress.Red color indicates that Record has problem while syncing with desktop database. icon on this screen shows information related with record syncing process.