Questions on Data modelling on basis of file server

[Qliksense_Ultra]

Hi SAP community, I have some questions on SAP Analytics Cloud SAP Analytics Cloud, data modeling 

Setup: My company used to use BW4 Live connections only, but since 1 week we setup  a SAC fileserver. I'd like to use this technology setup for a) building custom dashboards, that (partly) do not base on SAP (BW) data, and b) investigate how to get rid of now-excel-based data transformation/processing workflows. Also we will try to migrate some Qliksense-based dashboards to SAC.

So coming from that, I would like to know best practices etc on data modelling, as basically I will act as a multiplicator to the company. I've watched a lot of YT videos already (whilst working with SAC since ~4 years now).

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1) Data models can be edited later on. However I would like to replace a source by a newer version completely, as new data fields may have been added and other need to go. Is that even possible? 

2) Can I add more than 1 file as primary data? Example: I have exports from legacy source systems, which are limited on number of rows/size and want to load the incrementally. After that "facts" load, i'd like to enrich the data with steering and master data tables. If you know Qliksense, you know what I mean. 

2b) Can two+ models be combined? How? 

2c) any chance of actually doing this not low-code in the modeller but in a "script"?

3) For usage of data combining in the modeler: Is it really required to use the "classic" modelling way? 

4) Can a live connection be combined with other data sources (such as XLS tables) without using blending in the story (which is a) too slow und b) actually not a "join" or "combine")

5) Is there a possibility to generate reports (in XLS or PDF) in a scheduled way? 

6) Is there a possibility to snapshot a SAP BW query output in a scheduled way? 

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A lot of questions. I tried to be precise. Any input highly appreciated. Thanks!