Confused About My Options

At my organization we are looking to start using Power BI and I would like to get the story straight on what options we have. To start, I should mention that we will be connecting Power BI to a live SSAS cube (on premise) for the majority of the data we will be consuming. We have actually started building out dashboards in Power BI Desktop and will soon be looking to distribute them to people wthin the organization. This is where the confusion starts. I'd like to start by asking a few questions:

1. In order to distribute these reports in one centeralized location, are my only options to publish them to app.powerbi.com or purchase Power BI Premium and host them on premise?

2. For hosting on app.powerbi.com what excatly needs to be purchased? Do all consumers of the reports/dashboards need to be signed up for office 365 and have a Power BI Pro license?

3. Are there multiple Power BI Premium tiers? I'm not understanding why someone who utilizes Power BI Premium in the cloud would pay the same amount as someone who keeps their reports on their own server. Can someone explain this?

I am pretty confused at how this all works as I am used to using tools like Qlik with specific user licenses, so any help is appreciated. Thank you.