Where to Live in the Lisbon area

Hi!
I'm moving to the Lisbon area with my fiance for a few months this fall (september-december). I'm interested in living in Cascais/Estoril and was wondering if anyone could give me some advice on living there. I know it's a wealthy area and was wondering what the cost of living is there: one bedroom apartment, cost of restaurants, cost of cafes, other costs, etc. We are both students but love the idea of living near the coast and it seems to be a place where rent is cheaper than in central Lisbon for what you get (my dream is a balcony with a ocean view where I can do some work!).
Also, I was wondering if people ever do work in coffee shops/cafes in Portugal. I know in some places this is not really the use for cafes (I'm from the US, so its the main use for coffee shops here!). I'm considering this because I need to make sure there are few good places to do some studying. If we lived in downtown Lisbon this would be more accessible to the university libraries...
What do you think? Thanks for your advice!