could I use the online wallet to apply all those hard fork in December and January? I have been known that for example the Coinomi bitcoin.com could help to claim for the hard fork, and seems easy to do, is that ok to perform the claim in a online fork? Is there anyone has a user experience to do this way? which one is the best? many thanks!
Do not use online wallets.
A lot of hacks have occurred this way.
You can import your private keys to Coinomi wallet and use that instead.
Coinomi runs on your phone so it's safer than using online wallets.