You absolutely need a separate bypass capacitor for each of these two IC's. The MAX232 is pretty noisy and needs both a 0.1 uF and probably a 2.2 uf tantalum capacitor at Vcc, aside from the several cap's it normally uses.

The 805x device, whichever it is, probably needs a .01 in parallel with a 0.47. For high-frequency parts, I use a 220 pf in parallel with a 0.1 uF, but others may have different preferences.

My boards typically have one 0.01 uF cap per IC, and, for the ones that use significant current.

The only negative effect of too much capacitance on Vcc is a slower Vcc rise time.

RE