Visit to Medellin soon

Hi guys I am new to the board and would like to request any insight which would help me plan my daily activities. I will be arriving Jun 17 and will stay for 20 days. I need a recomendation for accommodation close to a gym and supermarket. I see lots of options on line but would appreciate any suggestions to narrow down the choices.
Also, Is immigration / visa given at the airport or must I get it before?
Anyone know of a local guide for the first few days?
I have lots of other questions but they can wait for now.

For a gym:
https://www.google.com/search?ei=i3cIW7 … JWybhAGrRY

For a supermarket (and there are many from small to large, almost in every neighborhood):
https://www.google.com/search?q=medelli … p;ie=UTF-8

For a guide:
https://www.showaround.com/locals/colombia/medellin

For accomodation you could explore Airbnb:
https://www.airbnb.com/s/Medellin--Colombia

If you are a bit more adventurous, for apartments:
https://medellin.locanto.com.co/Apartam … iendo/301/

And if you're even more adventurous, for rooms:
https://medellin.locanto.com.co/Habitac … iendo/302/