First I want say that I love the tutorial. It is just awesome. One of the best tutorial I have ever seen. Nevertheless, I still have some questions.
I managed to install and setup the wallet on rasPi 3, no problems, just followed the steps. I unlocked the wallet and transferred the qtum coins. After some time when I executed the following command:
~/qtum-wallet/bin/qtum-cli getstakinginfo
it was returned the following:

{
  "enabled": true,
  "staking": true,
  "errors": "",
  "currentblocksize": 1000,
  "currentblocktx": 0,
  "pooledtx": 3,
  "difficulty": 2128098.48440742,
  "search-interval": 445306,
  "weight": 2095900000,
  "netstakeweight": 915562123492605,
  "expectedtime": 55914858
}

However, after a week I am still not sure if I am really staking, because my balance did not change and when I run:
~/qtum-wallet/bin/qtum-cli getwalletinfo | grep -E 'stake|balance'
I get:

  "balance": 20.95900000,
  "stake": 0.00000000,
  "unconfirmed_balance": 0.00000000,
  "immature_balance": 0.00000000,

My questions are:

1. Am I staking already?
2. What does "stake" in qtum-cli getwalletinfo mean?
3. Do I have enough coins to stake or maybe there is no point to stake if you have less than x coins?

I really wished qtum staking (at least on raspeberry pi) was more transparent (like neo). Thanks for all the answers.