Yes, we have lots of things like "Tano". One of the characters in the Eternauta
the one who dies first leaving the house to find his family
is nicknamed "ruso". Ruso is Spanish for "Russian", but in all probability, the character is not of Russian ancestry but Polish or Jewish. We also called pretty much every East Asia person "chino" (Chinese) no matter if they are actually from China or if they are from Japan, Korea or even Philippine (we had very few Philippine inmigration, but there are many Chinese, Japanese and Korean people).
I should probably are that we called "negro" every person with dark skin, like me, for example. I am what people in USA call Latino or Brown. But in Argentina "negro" could be a friendly nickname. Sometimes it is used with a derogatory intention but most people have a dear friend who is nicknamed "negro" you will notice for context.
About Doctor Who, yes, definitely.
Even if the regeneration had been in somebody I like, for example, Martha Jones, I would have been irritated.
An amigurumi! Lovely! We have 3 of them (not done by me, I don't know how to wave). A baby Yoda, a BB-8 and a Pip Boy from Fallout. I am sure your friend will be ecstatic.