Re: Just returned...
Yes, I would brush up on your Spanish. Whereas in Houston (with a lot of Mexican people) the spanish speakers know enough english so that between the two of you, you can communicate, in Buenos A, most know little english.
You are gonna have a blast.
As far as 35mm, if you have a 28is mm wide angle lens to capture the width of the landscape and maybe up to a 210ish mm telephoto, you will be good. If not, still MANY opportunities.
Oh, I understand that it rains often enough to consider a good rain jacket (in Antarctica). However, we never had an issue....