Its not quite the same as the public VIP mining nodes. With those, you get a straight 2k? dilithium just from mining one single node for 1 minute.
With the fully unlocked fleet mine, you get 4k dilithium from mining all 15? 20? dilithium nodes. Around 3-4 nodes are located deep down underground which took me forever to find on my first and second attempts. Also, it takes roughly 30 minutes to get all the nodes. For higher level players, it may be faster and more fun to run STFs.
As for the costume, its a miner's outfit complete with hard hat and toolbelts. I have it unlocked on one of my characters just to see what it looks like. I'll post a picture of it when I can login.