The analog pins also have pullup resistors, which work identically to pullup resistors on the digital pins. They are enabled by issuing a command such as digitalWrite(A0, HIGH); // set pullup on analog pin 0 while the pin is an input. Be aware however that turning on a pullup will affect the values reported by analogRead().
I don't understand your question. You mean if there is a problem if you are using one as an analog input and other as digital output?
Details and CaveatsThe analogRead command will not work correctly if a pin has been previously set to an output, so if this is the case, set it back to an input before using analogRead. Similarly if the pin has been set to HIGH as an output, the pullup resistor will be set, when switched back to an input.The Atmega datasheet also cautions against switching analog pins in close temporal proximity to making A/D readings (analogRead) on other analog pins. This can cause electrical noise and introduce jitter in the analog system. It may be desirable, after manipulating analog pins (in digital mode), to add a short delay before using analogRead() to read other analog pins.
You also don't need to enable the pull-up when using the pin as an output (such as driving an LED).
OK i see your point but its not an accelerometer. The MCP23017 http://ww1.microchip.com/downloads/en/DeviceDoc/21952b.pdf is a port expander that's why i thought OP may have some use for it.
about the accelerometer.