Limitations when combining SharePoint Foundation (on-premises) with SharePoint Online plan 2 as Hybrid solution

Dear msdn experts,

As a part of our research to connect local MS SQL databases to SharePoint Online I would like to investigate the hybrid scenarios.

Q1:

For example, when the solution must be low-budget, which limitations will I get when I deploy a Hybrid scenario with SharePoint Foundation 2013 (on-premises) with SharePoint Online Plan 2 (wave 15: version 2013)? Will the whole SharePoint environment be limited to the functionalities of SharePoint Foundation?

Q2:

Are there any options to connect the local MS SQL database with a list within SharePoint Online without the need of installing SharePoint on-premises?

Thanks in advance.