Thanks for the answers. I did some research after posting this thread and I came to same conclusions as you guys. A hybrid cannot fit a suspension fork. I understood it immediately when I did some calculations with geometrycalc and compared my bike's geometry to a proper mtb. And you guys confirmed it.

As you suggested, I have been thinking about putting on wider tires. Actually I have been thinking of it a long time, but I have never bought them. But now I will. I think the frame can fit something between 50-55 mm tires so I have been thinking about Schwalbe's Big Apples or Big Bens. But I still do not know what is the difference between balloon tires and normal tires as wide as them. I also drive in the wintertime and there is a lot of snow in the wintertime here in Finland, so i'd like that the tires would handle some snow also.

I probably will practice those things [MENTION=424051]Ironfish653[/MENTION] Actually I think my bike would be pretty optimal for that cause it's pretty light and easy to handle.
[MENTION=197614]fietsbob[/MENTION] I'm overall satisfied with the bike so no need to sell it. It is perfect for everyday riding and rigid fork is good in the wintertime. If i get into trailriding, I'll buy another bike (a proper mtb), but I don't think it is going to happen in near future.

Thank you guys