I find it pretty confusing that the voice speaks out question and answer as if it is one sentence. At the very least, I would expect a pause between the question and the answer. Better, if the voices were different.
Hmm, yes, but many Finnish first names and last names (that are not loans) are nature names.
Nowadays you aren't really allowed to have/give an established last name as a first name, so first names such as "susi" (wolf) are not common, but they are instead used as last names. So while -nen and -la for instance are common endings to last names, there are plenty of last names with no particular ending. Such names include "Kivi" (stone), "Koivu" (birch tree), "Virta" (stream), "Ilves" (lynx) and so on.
Curious is the "Not allowed to give last name as first" actually something in Finland? Or are you speaking just generally that people don't often use last names as first names? Because in U.S.A you can use whatever name you want. I've known more than one Jameson, or Robertson, as first names. which are century old last names. Would seem pretty absurd to restrict a name choice because someone else has it as a last name.
Name laws are much stricter here in Finland than they are in many other countries, including the U.S. However, if you are an adult and want to change your name, the laws are less strict than if you are a parent naming your child.
Yes, you aren't really allowed to use last names as first names although exceptions can be made if you provide a good enough reason, e.g. it's a traditional name in you family etc.
I think you might be confusing "sinullä" with "sinä"? In case you meant "sinulla" with "a" instead of "ä": using "sinulla" here would be incorrect; it's the adessive case of "sinä" and usually indicates possession. You can use "sinä" instead of "sinullä" in your sentence, though it's also fine to omit it altogether.
I think it could. The meaning is slightly different, but I think the Finnish sentence could translate to either meaning. "Valmis" could be either ready with a task, or ready to go. Ready with a task fits "done" better, and ready to go fits "ready" better. Again, in my opinion.