no you can only know this and need to change it
they can if they have a code cracker, and if it is a wpa then they will need a really large dictionary but a wep is easy to crack
go to your web browser and type in the url 192.168.1.1 and hit enter password is admin and username is empty GO CHANGE YOUR PASSWORD TO A PHONE NUMBER OR SOME NUMBERS YOU WILL REMEMBER I THINK IT HAS TO BE A CERTAIN LENGTH