call eliot a dudette, she likes it :P

Don't use it for females! If you must you can use "dudette".

Dude is used for guys. When you call a girl "dude", it implies that she might be like a dude, or that she is like a guy or man. Most girls take offense to it. Even so, it's best to just use dude only for guys. Dudette is appropriate, but I don't know anyone who uses it. You can also say, "hey, girl", but it is very slang-y and the girl might think you are flirting with her (and react accordingly). "Girl" is safe to use with a girlfriend, but you probably shouldn't use it with a close female friend that you don't "like" that way.

you can but it depends on the person if they are close enough with you that they understand you and are ok with it. it would not be right or wrong, but its not common

i would just say hey or hi, i would not add any additional things to it. some people say things like "whats up girl" but thats just another common phrase. you really dont need to add anything. a lot depends on where you live. in my area, people will say "whats up girl" or also there is a lot of spanish speaking people so sometimes they also call "hey mama" or " mami" it depends on region too.