For a small site having 'clean' urls can be a nice feature. Like in Wordpress and most other cms.
I was wondering if using subdirectories could do the trick creating a structure like:
that can usually be browsed without typing the /index.html.
An additional save and export feature for a multipage site could automagically rename all page-name.html into page-name/index.html and maybe process (sed.exe via a post save script?) all href too.
I really have no idea if there is an easy way to do that, but in this CMS era i'm used to see 'clean' urls everywhere.
What is seems your asking for is not something the app has control over. The app is a development tool not a webserver.
From what I understand is that I think webservers handle redirects to /index.html by default at only the root level i.e. website.com/index.html
If by default they handle at any level, sub or root /index.html then its just a matter of you prototyping your BSS project that way, like Chris stated in his response. Otherwise it's up to how your webserver is programmed and will serve up websites.
I believe that this type of URL (website.com/where-we-are/) is referred to as a Friendly URL. And my understanding is that you have to program your webserver to redirect Friendly URLs to an actual file or database entry which is what I think Joomla actually does.
I'm not sure what you mean by valid, but that is one of the ways to do it. Of course there are other methods, but they aren't as easy. There can be SEO problems if you make the url too long, or include underscores. ex: domain.com/how_to_optimize_seo/ Use hyphens instead or some other format. Tool for seo analytics: http://seoexe.com/website-reviewer Also, SSL has an impact on search engines like google, so I suggest making your site secure somehow.
I concur, but that does have a negative effect on the page's speed and caching. I typically use .html for smaller sites so clearing cache is easier. Here is my site that scored 100/100 on Google Pagespeed insights: https://www.cbenn.ml
Alternative, you can make the folders and have them redirect to your html file so no negative effects are in play.