The currency seems to depend on the country where the money is requested. I got compensated for a denied boarding on a Turkey-Canada flight in Canada and got it in canadian dollars.

If you are a UK citizen as the tag "uk-citizens" implies, you do not need visa for short stays in Turkey afaik.

@Mark thanks. Does this impact visa validity periods? I.e. would it be counted as visa overstay if the flight was scheduled for 23:50 of the last day of visa but the doors close at 00:10 next day?

"You'll leave Sweden when your flight does" Could you please provide more details? Does this mean the scheduled departure time before any delays, including all the delays, the moment of crossing the border of Sweden during the flight, or something else?

The words "professional" and "alias" are coming from the question itself, not from the law firm. It seems like in this question they are looking for more or less official names (including stage names and alike) but not necessarily social media nicknames, since later in the DS 160 form there is a question specifically about social media accounts. IANAL, of course, but at least that's the way I have always understood and answered this question.

"You have described using the name “HJDJASD Mahmud” online. This is another name, and you used it to identify yourself." Do you mean that for the purposes of DS160, social media nicknames are treated in the same way as actual names?

From personal experience, it is possible to receive voice calls over the Internet by installing an extra app (at least for the MTS mobile operator). Posting only as a comment since not about sms but could still be useful.

While the UK immigration may not be concerned about the itinerary, the air companies (usually) want to make sure the passengers do not arrive to their destination before their visa allows them to. In the case of OP it should be fine anyways, since the arrival is on the 29th.

"You understand that no, you can’t just waltz in, provide a service and be paid for it, under B-1 status" it would be good to have more than just appeals to logic for this part IMO. From the linked document it is not clear if the payment from a US company to the B1 visitor can be equated to the payment from a US company to a UK-based company that employs the B1 visitor.

@Midavalo As far as I understand, we can only speculate until the OP states their citizenship (there have been questions on this site where the initial assumptions of OPs were wrong). That's why I tried to give a more generic answer, if they need a visa, it is likely B1. If they are allowed to apply for an ESTA, it seems to cover B1, so should be fine too, but I have no personal experience with it.

@Midavalo The OP asks which visa they need without stating their citizenship. If they need a visa in general to go to the US, it is likely to be B1 for this particular case. If they do not need a visa, ESTA seems to be applicable for B1 purposes, but I have no personal experience with ESTA.