Min favorituppfinning är kanskenog datoren.

"kanske" implies that you're uncertain. This would be fine e.g. if you were writing/saying this specifically to answer a question about your favourite invention. Here, on the other hand, your sentence seems to have been written on your own initiative, so it just comes across as strange that you would then start by showing that you aren't even sure if it really is your favourite.
"nog" also has an element of uncertainty to it, but I would roughly translate it to "probably". (NB I understand that in Finland Swedish "nog" is closer to "surely" or "certainly".)

Den hjälper mig med skoljobb och ger miMed min dator kan jag jobba med skolarbete, och genom den får jag ett sätt att ge liv åt mina tankar.

The previous sentence talks about "datorer" (i.e. plural), so it doesn't fit to then start the next sentence with "den" since it isn't clear what "den" refers to.

Homework, writing essays etc is called "skolarbete". Even though "jobb" and "arbete" are usually interchangeable ("arbete" being a bit more formal), in this case they are not.

I've rewritten the sentence to make the computer less of an active subject. See my comment below regarding "hjälper".

I'm not sure what you mean by "ge liv åt mina tankar" here, in the context of computer usage. That phrase in itself is perfectly fine, but it isn't clear how a computer helps you to do that.

Datorer också hjälpegör det också möjligt för mig att prata med människor från runthela världen som jag inte kunde ha annars även träffathade kunnat träffa annars.

If you use "hjälper" you're saying that the computer has an active role, rather than it being merely a tool that you're using. I've changed it to "gör det möjligt", i.e. "makes it possible".

You could either have "människor runt om i världen" or "människor från hela världen".

In this case, you could put "annars" either between "jag" and "inte" or after "träffa". Either is fine, but the latter sounds slightly more casual.

Jag vill lära mig mera om datorer i framtiden, kanske ipå universitet.