Ooh, back to my previous topic... as it first seemed that only the hose was cracked and leaked, I changed only the hose.
But tonight I got quite some experience - standing by the road for the very first time. At first I thought that something really bad was going on, I heard two bangs and then stopped by the road, the bike not starting again. After a while and one helpful gentleman later, the bike started and I could drive about 500 metres and the same thing occurred (ok, without the bangs, but stopping just the same). After consulting with my well-experienced friends, I checked the gas level (there was some gas, although not much) and switched to reserve - and thanks to this, I am now home. And very grateful.
So I guess that yes, this is now the time to change the petcock! Or is it just a quirk of this bike that when the gas level goes rather low (but it's not out of gas), it doesn't get gas normally anymore?
Maybe I'm just so much newb that I ran out of gas like a normal newb does at least once
I do hope that all this was only gas-related because I was quite afraid of something more serious at the moment.
Two other lessons: always take your phone with you! And always stop and ask whether someone needs help. Thanks a lot to the guy who stopped.