Finnish is pronounced extremely regularly. The way it's written is the way it's pronounced (in almost all cases).

No, there is no variation on pronunciation. They sound exactly the same when spoken.

The only way to infer what's meant is from context.

My favourite homophone example is a 92 character poem in Chinese[0], where every syllable is a slight variation on Shi.

[0]https://en.wikipedia.org/wiki/Lion-Eating_Poet_in_the_Stone_...

Interestingly when I showed the actual text to my wife, who is Chinese, she didn't understand what was funny about it until I asked her to read it to me, when she burst out laughing. That's when I found out she doesn't sub-vocalise, where I do all the time.

These aren't really homophones though, right? Because they differ in tone?

There are only 4 different tones, so by the pigeonhole principle there must be lots of homophones.

On the other hand, most of the characters used to be pronounced differently when they were still commonly used as individual words, so the poem only works because it mixes modern pronunciation with classical grammar.