And I understand, that calculate it as the sample mean will be wrong. Maybe more correct is a weighted mean based on their Max Supply, Circulating Supply, Number of transactions or Volume - I don't know.
I honestly don't see much point in yet another index, unless it adds a completely new flavor of how we can rank coins based on different metrics instead of what index sites such as Coinmarketcap already provide.
Every metric you listed already exists, where some index sites even allow you to compile your own top list of crypto currencies based on metrics you think are important. It's a crowded part of the industry which is very difficult to penetrate.
I might sound a bit negative, but unfortunately I can't make it look more pretty.