Architecture question: PBI or Azure AS

Hello All

I need to create a tabular model on which Power BI reports are based. I have several architectural questions:

1- PowerBI Pro or Azure Analysis Service? What are the different criteria for choosing one or the other?

2- Import Data or Direct Query? I understood that we must favor the Data import mode unless there is a need to have the data in real time. The other criterion is also related to the volume of data because beyond 1 Giga of data the import mode does not work? Is there a way to estimate the model size before creating the model?

Thanks for your help.