couple simple questions for designs

first, i would like to say thank you to all that have helped me in many ways. ya'll have made it possible for me to enjoy something that i always wanted to try and do and even the small things im doing now are helping learn so much.
so with that buttering you guys up a little (LOL) here a couple small questions.

1.)
is it better to control the input into a LM386 or control output of LM386 with the digital pot (MCP41100 - 100K)
i think the impedance and/or voltage would still be within specs if i controlled the output of the small amp, correct?
setup with 200 gain on LM386.
reason im asking:
i have a 328P with 2 - MCP41100 with TDA2050 (32W amps 1 - left and 1 -right channels)
i am using the 3.5 headphone jack as the input from phone, ipod,... into the MCP and i can hear clicking of the pot as i lower to off.
i'm thinking the TDA2050 output would be too much power through D.Pot but how about a LM386.

2.)
is it necessary to use a bypass cap on every input of IC.
ATMEGA328P
pin - 7/VCC
pin -20/AVCC
pin - 21/AREF

can one '104' film cap (or whatever size needed) be used by all pins or does each need separate bypass caps?

can one '104' film cap (or whatever size needed) be used by all pins or does each need separate bypass caps?

One for each pin.

By wiring all the pins to one bypass cap you also wire all the pins together.

By wiring all the pins to one bypass cap you also wire all the pins together.

simplest things get overlooked alot.
i should have seen that.