What is "¿Cómo quedamos? "
I am from Argentina and we use this phrase all the time. Maria-Claire is right. It is used for summing up time and place for plans (and you can use it without the "dónde" and "a qué hora"). My humble example:
A- "Entonces, ¿cómo quedamos?" B- "Mirá, nos vemos en la Catedral a las 17.30. Te mando un mensaje de texto cuando esté llegando."
That would be the expression in use
Quedarse is a great verb to learn right away, it is used in a lot of idiomatic expressions: quedar limpio (to be broke) quedar mal (turn out bad) quedar bien (the opposite) quedar de acuerdo (reach an agreement) quedarse muerto (to be dumbfounded) quedarse con la boca abierta (be very surprised) quedarse ciego (to be left blind) . You can say something like 'me quedo sin dinero hasta el día quince'. Such a useful verb!!!
My guess would be:
How are doing?
For example, you are eating in a restaurant and the waiter comes over to see how you are doing. He says, "How are we doing (with the meal)?"
Or you're filling out a form and the person who gave it to you says, "How are we doing (so far)?"
where shall we meet and what time?
It's so pleasing to see that my Collins dictionary does come up with the correct answer. As you would expect, Heidi confirms this.
¿Cómo quedamos? - Where shall we meet and what time?
Maria and Lucho got it right:
How are we meeting (literally), that is where and when?
....where shall we meet and what time?
I believe that would be "¿Dónde quedamos y a qué hora?"