I'm about to recap my board (Soundcraft 200B) which is getting hissy on some
channels, and in researching options I found some discussion of bypassing
electrolytic capacitors with film caps in parallel.

The textbooks I've been using to teach myself basic electronics don't
discuss this practice, so before I go ordering a bunch of components I may
not even need, I have a few questions:

1. The benefit of bypassing electrolytic caps is typically in improved high
frequency response because the lower value film cap will pass higher
frequencies better than the higher value one, and vice versa? There's a
counter argument about phase shift--how much is that worth worrying about?

2. Are there places where this isn't useful/helpful/worth dealing with? I'm
guessing that the 47uf phantom blocking caps would benefit, but what about
interstage coupling, etc?

3. The value of the film cap should be 10% of the electrolytic. How critical
is that value?

4. In an existing design, you just connect both caps at the same point,
soldering the film cap to the point where the electrolytic attaches to the
circuit board? In this case there's room on the other side of the circuit
board. Since all the points on each side of a parallel network are
electrically the same point, this would work, right?

Thanks!

-jw