With the hard fork approaching I saw bitcoin.org suggests to shun away from the hard fork adopters such as coinbase, blockchain and xapo? Any good online wallet to use?
No, they are either:
1. Unsafe
2. Have zero guarantee of giving you access to your coins.
How hard is it to get a desktop wallet? Its the only way you can get full access of your coins.
Does anyone know those which online wallet those big exchanges such as bitstamp, kraken, bitffinex use? Do they use 3rd party hot wallet or they are using their own proprietary online wallet?
It's impossible to tell. However, they are likely running their own wallet as the backend. Using a third party for the hot wallet would be way too hard.