Hi,
to be honest: For such large tables, I’d actually recommend to not use TablePress. Not only will you experience slow loading times on the frontend, but you it will basically be impossible to use the “Edit” screen of TablePress.
TablePress simply was not designed with such large tables in mind (which actually are more like simple databases, probably). It’s intended use case is to make it possible to quickly show static data, that is not too large.
Regarding your questions:
1. Yes, uploading such a file should be possible, but you might run into memory or processing time limits on the server.
2. No, this is not possible unfortunately.
So, in summary: For such large tables, I’d actually suggest to use a custom PHP/mySQL solution (e.g. in WordPress Page Template, to be able to use the WordPress PHP functions), and then to load DataTables manually. This would also make it possible to use the server-side processing. Unfortunately, I don’t have any experience with this, so I can’t help here, sorry.
Regards,
Tobias