As Lefty said the type of capacitor you're using is almost more important than it's value, generically higher values are better for coupling as a higher capacitance will have a lower impedance at any given frequency. For DC block you need to define exactly what you're going to block. ANY capacitor will block straight DC, but in the real world there is almost no such thing as true DC, all signals invariably have an AC component, primarily ripple from power supplies and load changes. Switch modes use a higher frequency than mains power upwards of 100-500khz so it's ripple will couple better through a capacitor rather than the 60hz from a wallwart supply which pretty much any capacitor will block. Bypass is just as tricky as you want something that will shunt as much of the undesired frequency as possible while keeping insertion loss for your desired pass signal as low as possible. It's really a complex subject, especially if you want sharp band cuts or narrow pass bands. Filter topology is like black voodoo to me =)
I know ceramics are generically used for lower values and higher frequencies, electrolytics are primarily power hold up and coupling capacitors for mid power audio, I think they have a high inductance and their impedance is very non-linear over a certain range. Don't know much about the internal structure of tants, other than they're voltage sensitive and are in between ceramic and electrolytic, usually being of a high value but with a small package size, I don't think they're particularly thermally stable though. Thermal stability can be a major determining factor in choosing a capacitor type. Different chemistries even in the same capacitor class can provide positive and negative temperature coefficients.