1. Does the same TA for stocks apply for crypto trading?
No. Although some claim that Technical Analysis can help you make reasonably accurate predictions about the future price movements of a cryptocurrency, I don't believe in it. The cryptocurrency market can be traded upon by luck, listening to what your feelings tell you and researching the coin & its community.
2. Can you recommend me a few best books for TA crypto trading, the bootcamp I took was 5 years ago, so I have forgotten a lot of what I learnt.
I don't know of any and if there are any, I recommend you not to waste your money on them. It's not going to yield you anything useful. It will take a lot of effort to learn it correctly, cost money to buy the book, takes a lot of time and will probably not yield you much more than just trading cryptocurrencies the way they are meant to be traded: By research and redoing.
3. Can you recommend me some websites related to crypto currency trading? I would like to follow other people signals and analyze them.
There are some reasonable traders at steemit.com . I recommend you to follow the ones you think are pretty decent.
I don't follow any, but I just recommend checking out some tags like crypto, cryptocurrency, trading, bitcoin and more to find some good analysers.
As I said earlier, I don't do these kinds of things and I can't guarantee you any profits.
4. Is there an exchange with demo accounts to try first?
Not that I know of, but I tried "imaginary" trading a while ago. What is that? It's easy:
You create a google document.
You give yourself a certain balance and put that somewhere in the doc.
Then you start imaginary trading. Find a good exchange to buy/sell your cryptos on.
Note down the details of each trade, at both the selling and buying: Price/Coin, Amount of Coins bought/sold, Total Price, time and anything else you think is worth it to add.
I did it too and I figured out: Trading is not my thing.