Re: Best Way to Design PowerBI Reports with Access Database stored in Sharepoint Online

 You'll need to install the on-premises data gateway. I would create all your reports in Power BI Desktop first, this will provide you flexibility in so many ways. Create and use a Group Workspace to publish the reports to, this will allow multiple users to be able to manage the reports instead of just one person.

When you deploy the Desktop reports, a dataset will be created for each set of reports you publish. The dataset can be scheduled to refresh up to 8x per day, this is set up and done in the Service.

There was a new way to easily embed into SharePoint Online, but it does require certain version etc., but it's really straightforward. Otherwise you would need to do some custom DEV to embed.