You can here he melody in your head alot of times when your write lyrics.
yes but you play guitar so you can make that melody later. BUt if you don't, then its still not a song..
Yes a song is not a song without music, you can sing the melody though. Sometimes I write lyrics keep them aside and they end up fiting music that I write down the road.
that's easier to do with simple songs, sometimes i come up with a chorus first and build it from there. With more technical stuff i find i have to do the music totally sepearate