Kentico 8.2.
I've got a layout "master" file - the creatively named Master.ascx.
I've got three web part zones in the layout: header, main and footer. Main just includes a content placeholder which is overridden by the next layout down - home, standard, whatever.
I could just drag and drop web parts onto the header and footer web part zones on to the "design" tab, but I don't want to for a few reasons:
Is it possible to just hardcode a web part into my layout?
To answer your question, no you cannot hard code webparts in your layout. Simple reasoning is webparts are not part of a layout, they are part of a template . The webpart definition for each template is stored with the template in the database as XML. You can see this by going to a template and selecting the Webparts tab and it will display all the XML for each of the webparts on that page template.
Understand where you're coming from with your 4 points. What you also need to consider is:
The point of the CMS is to be dynamic and database driven. Not everything can reside in the file system, database or a code repository. Kentico has some very strong developer tools you can enable like workflow, versioning, and check-in/out.
I'd also enable your DBA and ensure they have a valid backup and recovery plan in the event of some disaster.