Can capacitors be replaced with higher capacitance ones?
The IC that you are pointing out is a 3W (or maybe a 2x 2W) stereo audio power amp.

The one in rev 2.6 is a SM7496L, which I am having a hard time finding any info about, but it is essentially the same thing as rev 2.8 just a different manufacture, so it is probably safe to assume that circuit should be the same around them. This means it should be safe to put a larger capacitance value on it.

For the group of 3 with one missing, it looks like these are next to something that is probably a voltage regulator with a big heat-sink on it. If this is the case, go read the answers for this question Capacitor Sizes for 7805 Regulator

For the other 2 capacitors, these look like they could either be used with the 2 diodes or could also be for the voltage regulator.