Where in my iPod Touch I can write my name and phone number, so if I lost it or it been stolen and found by the police (as I read that happened), someone could call me to go get it back?
No, but you can create an image that has your name and contact info on it, then use that as your lock screen wallpaper.
You could also create a note on the device or an "emergency/lost" contact in the address book, but both of those require you to not use a passcode to use the device. A wallpaper with contact info works even if the person who finds your iPod can't unlock it.
If you are really fussed about this then you can go to an engraver and get your name and phone number engraved on the back.
You can also install Find My iPod Touch if you have a 4th gen iPod Touch. I'm not sure if it works on earlier models, but it might.
I put a sticker on back containing my work contact information in large print. Easy to read even if the batteries are dead.