As to your .ISO burning question, you haven't mentioned which Operating System you're running. If you're still on your old Windows 8 Pro then I can't be sure what Creator NXT does in that OS, but in Windows 10 there's quite a difference between NXT4 and NXT6.
If you right-click an .ISO file with NXT4 installed, you will see that the default action (what happens on a double-click) is set to Open, and you will find that a double-click opens the ISO with Roxio Creator. This is set up by the NXT4 installer.
However the NXT6 installer doesn't do this. The default action is left at Mount, and a double-click will attempt to mount the ISO. See the picture below. NXT4 on the left, NXT6 on the right.
Now you should also see options similar to, or same as those shown on the right above to burn the ISO if you don't want to go and manually run Creator's 'Burn Disc Image' or the separate 'Roxio Burn' application.