om with location is to the … of … – (till) vänster om huset 'to the left of the house'
på in framsidan på huset is like of in the front of the house, it's just that we don't use av that way (it's not totally wrong in this specific case, but på is the most idiomatic way of saying it).
A façade is a specially constructed front side of a building, an architectural feature that was common years ago, especially for buildings on the main street in the business section of town. Sometimes the façade would have a structure higher than the normal upper ledge of the wall to support special decoration, sometimes the year of construction, often the name of the business. The front side of an ordinary house or building would not be a façade.
"Façade" can have the sense of "false front," and this word can be used figuratively:
"Her flawless public façade masked private despair." https://en.oxforddictionaries.com/definition/facade
It's not quite natural. Possession is usually shown with 's for people and with "of" for things. But actually, I also think "side" is completely unnatural in English. I would just say "the front of the house" ... but logically, your answer is correct - just a bit odd - and you're learning Swedish rather than English, so it should be accepted.
You can definitely use 's to show possession with things, all respect to BenUserName, so don't think it's very unnatural.
Saying 'front side' or 'back side' of the house is possibly a bit redundant, but it wouldn't be wrong or unnatural, especially if there is a practical reason to say it, like if you're doing work on or outside the house. Also, we often say 'the front of the house' or 'the back of the house' or 'the side of the house' to refer to that general area right around the house, not just the vertical surface.
There a limitations, though. I wouldn't just generalise using definitely.
In English the -s genitive is used for people and often also with animals (the horse's owner), places (London's nightlife), countries (England's coast) and institutions (the government's report), as well as with times (yesterday's news, in a week's time).
You would however never say The house's front side.