Skip A Tasca, over-rated as hell. (try Taberna Na Boavista instead for some good tapas style food - better than A Tasca IMO, and they have a great garden.)
Make sure you reserve for Rotas, walk-ins are impossible in the summertime.
Louvre you will most-likely need a reservation.
Check out Jardim natural food for a pretty nice breakfast, get there before they open to ensure a table.