Multiple buttons on 1 analog VS one digital per button:Power Consumption
You want digital with a pull-up. Most microcontrollers can provide the pull-up internally, but you can also choose for an external resistor if you want a higher resistance value, for instance. Not that this value matters much because there won't flow any current if the button isn't pressed. Only for the short time the button is pressed there will be a small current; if you use 100k\$\Omega\$ pull-ups you'll have a few tens of \$\mu\$A with a duty cycle probably as low as 0.001%.
A pull-down instead of pull-up is also possible, but is less common. If you use it, be sure to switch the internal pull-ups off.  

Especially for tact switches which aren't operated often a 100nF capacitor parallel to the contacts is a good idea. The capacitor will be shorted when the button is pressed, and the small current peak will keep the contacts clean.