I just wanted unique names for my craft. And, althout I'm a fairly decent programmer, i'm not going to learn any UI for KSP until 1.1 drops, since I gather it's likely to be very different.
The first launch will anounce "Initial Launch". Every subsequent launch of the same vessel (or vessels with the same name) will give you be "Launch: <vessel name> <number>". It only knows about launches it has seen, so if you want unique naming, I'd recommend using it from the start.
It won't attempt to number vessels that already end with digits.
If you prefer roman numerals to arabic numerals, you should be able to find the setting to change in the save file. It's pre-vessel-name currently.
Raw stats are from the beginning of time until now. Each follower and download entry represents one hour of data. Uneventful hours are omitted.