Of course we still speak Finnish. Weird question. Has any country given up their mother language before?

Even when Swedish is our second language, I think the law says that any shop has to serve us in Finnish language. So yes, we speak Finnish everywhere and we are not going to quit. 

And to be clear:

We are taught English language since grade 3 (when we are 10). And I think the learning never ends even in schools. Even college and university of applied sciences teach you English.

We are taught Swedish since grade 7 (when we are 14). I think you can start it earlier in some schools. However from my anecdotal experience I would say that most people can't speak Swedish at all. 

Jäätelokone

*Imperfect tense and genitive since it happened before and you did the action

**This word can be left out. Especially since later you use "joku" again which doesn't give the impression that it is necessarily the same person buying the machine. It isn't wrong, but it sounds a bit silly to repeat the word "joku" to me.

***You are selling the thing in tori.fi so the ending is -ssa or -ssä depending which is more natural ending to say. I don't remember what this case was called. Examples like autossa, korissa, kaupassa, hississä.

****Since the part belongs to the ice cream machine, the "kone" is conjugated as "koneeseen" which I think is illative case.

*****I don't understand this part, sorry. If you wanted to say that you included the missing part after finding it, you could say something like "löysin osan ja lisäsin sen pakettiin/korjasin koneen". If that was the case, then I would move this sentence before the apologizing.

In the last sentence, I would specify that you send the ice cream machine to that somebody. It wasn't really wrong, but this way it is more clear in my opinion. Or you could just change the whole sentence to "Lähetän jäätelökoneen hänelle postilla".

Sorry if the explanation is messy.

"to see/ look/show"

Can you please show me where I can find eggs? Voitko näyttää minulle missä munat ovat?** 

May I see a different color in this shirt? Voinko katsoa erilaisia värejä tästä paidasta? ***

*When looking at something you need to use partitive. That is why it becomes lelua.

**"munia" isn't really wrong, but then it would have to be "Missä munia on?" So to keep "ovat" you would use "munat" instead. The nuance difference is that "Missä munia on?" could be said when you don't know which store has eggs. And "missä munat ovat" would be like asking from market staff if they know where they are in the market. But it isn't really wrong to use either when asking from the staff.

**Conjugation of the "paita" has to be elative case. I am not sure how to explain this one well. It is one of the more abstract uses when the object of question has to be conjugated like that when you are asking more info related to the object.