Lightning strike on a previous sector to the outbound to HKG to your return is not grounds for BA to deny EU261 delay compensation. So claim for that when you return home. They may initially deny it but push back. There is a lot of advice in the main EU261 thread.
you are also entitled to the duty of care elements which you have listed already (but the amounts are advisory limits imposed by BA and not by the regulation) so keep your receipts for your claim.
If you chose to stay in the airport terminal rather than book a hotel then there is no extra BA payment for that as it’s something you chose to do.
your various credit cards and own travel insurance may offer additional amounts as well as actual help in booking a hotel so check what help they can give you.