Can you please tell me how to exchange Bitcoin for EOS from online wallet https://bitcoinofficial.org to EOS wallet https://freewallet.org/eos-wallet ? I found the services of Changelly and Shapeshift - should I use them? What is more profitable?
It is much easier to use one multi-currency wallet with built in exchange.
Try Lumi wallet, they have changelly built in and support bitcoin, eth, eos and much more.
Also you can establish there an EOS account for free.