Seriously, we know less about your house than we do. In fact, we know NOTHING about your house.
Only you can answer your questions.

There are amperage limitations to circuits, not voltage. With Christmas lights though you'd be best served with a few 20A circuits spread around the outside of the house.

If you use LED strands and don't live in the Windsor castle, you really only need one outlet. I have GE LED xmas lights and can strand 25 sets together @33' per set.

How will you control the lights? Climb a ladder each day to plug/unplug them? Have you considered having those receptacles controlled by wall switches?

Switched outlets and a dusk to dawn timer.

Howe many depend on what you envision for the power demands of the lights you want to to run.
Smaller wattage stings (like LED lights) would likely make 15 A circuits more than adequate.

Spacing depends on the string lengths and how many can be plugged into each other (many use small wire ad 3 amp or less fuss).

If you want to be able to use remote controls for fancy effects you have the problem of providing access to the power lines for the eaves receptacles from the controller location.