It probably refers to him practicing musical scales on an instrument.
most of them do
No, they are considered bird which mean they have feathers. Scales are on most reptiles, but that is it. Yes, penguins have scales on their legs. Feathers are modified scales. Their feet might look a little scaly - but otherwise no.
I would interpret this to mean that you are an interesting person; watching you is as interesting as watching a movie.
If you mean music scales, you need to be more specific, there are all sorts of scales - A m(inor), E flat (major),D (major)...
means you live forever
If you say that watching an activity is like watching paint dry, you mean that it is very boring.
The scales.
Means to multipily the numerator and the denominator of a ratio by the same factor.
Watching over
He/she/it is watching.
Watching television
There are innumerable scales and the answer depends on which scale you mean.