When you import a Workbook or Power BI Designer file, we extract the data model from the file and host it in our back end. We then work against that hosted Data Model, not the workbook or PBIX file where it came from.
Power BI works with the Data Model. If the data isn’t in the Data Model, we can’t really do anything with a file (Excel Workbook or otherwise). You can have your data model in a couple of locations. Either in an Excel Workbook, a Power BI Desktop file or an on premises Analysis Services Tabular Instance.
You can set alerts around different parameters, but I am not sure if you can set alerts around the insertion of new data. Instead, I believe it is based on updates to the data you are currently tracking.
Set alerts to notify you when data in your dashboards changes beyond limits you set. Alerts work for numeric tiles featuring cards and gauges. Only you can see the alerts you set, even if you share your dashboard.
This was the best overview of Power BI’s raw performance I could gather
“My example data for this talk is a customized Tasks table from Salesforce. This real life data table comes from a client and is sanitized for confidentiality. The example has over 382,000 rows which isn’t a large table for Power BI. When the data is loaded into Power BI, the stored file size on disk balloons to over 500MB. In memory this data set occupies over 1GB.”