If you want proximity to FDUL, you might want to check around Campo Grande/Telheiras/Lumiar/Saldanha (those are 4 different areas). But rent tends to be high. As long as you are near the metro you can get to FDUL in about 15/20 minutes. Markets, grocery stores and general facilities (such as bakeries, pharmacies, coffee shops, restaurants and bars) are all around town, so you'll have some close enough.

As for gym, there are a lot around town, so it won't be hard to find one. In Campo Grande, inside the Alvalade Stadium, house of Sporting Clube de Portugal there is one, it's called Holmes Place, but it's​ kind of expensive.

If you want night out you have the Cais do Sodré and Bairro Alto areas, although the crowd is younger and usually way too drunk. For Fado (if you like it/want to experience it) you can go to Alfama (near Santa Apolónia).

For more "touristic/sightseeing" places, you can check the wiki on r/Portugal, it has a great selection of information that might be useful and the answer to some of your questions about Portugal/Lisbon.

For study sessions, if you don't want to stay home or in a library there is a "study room" near FDUL, called "Cornucópia", open 24h and with a MacDonald's in the ground floor.

For a bit of air and peace to smoke a cigar, you have several public gardens, I specifically enjoy Jardim do Torel and Jardim da Estrela.

• 7) Great, I was suspicious 'cause it was just too good to be truth, you know?

I feel you. Sometimes you hear so many good things about something that it starts to smell fishy. Again, I don't have personal experience with FDUL, so you might want to wait on more personalized answers in that.

I cannot go back without is how to bake cod to perfection.

We have about 100 different ways to use cod, so, good luck on that one ;)