Fusion360 needs to connect to the internet at least once every 2 weeks, so yes, you need an internet connection.
https://knowledge.autodesk.com/support/fusion-360/troubleshooting/caas/sfdcarticles/sfdcarticles/Does-Fusion-360-require-the-internet.html
Welcome to CadTutor Alex_Freelancer.
I suggest looking at your 3D Snap Options, and setting them accordingly.
By the Middle of an Object might you mean the Centroid?