If all you want to do is help readers find content, it’s easy enough to set up a bespoke web search through Google. Algolia.com is another solution.
If you have a folder of html files (or better yet, Markdown) consider a program like mdbook (free). You can call mdbook from within RW, but it is created separately. You will get a table of contents for your files–as detailed as you want it to be–along with a general search function that lets you search the content within the folder.
There’s a bit of a learning curve, especially if you don’t know Markdown (come to think of it, could you use a Markdown stack to generate Markdown? I don’t know). You will be left with a folder full of html documents which you can then upload and link to from within RW.
As to your #1, I don’t think you can squeeze an image into a title name, but you can display the title as text for each page. #2: it’s a full text search; how you arrange the pages is up to you. #3: All of them; or at least, all the ones you wish to include. You will create the ToC in Markdown, if you don’t want a page to be included, it won’t be. I think the mdbook processor skips pages that are not included in the ToC, but I’m not sure about that. #4: this is not a stack but it is Markdown and html. Ultimately the web is html so you shouldn’t be put off by this.
I think RW users (myself included) always look to Stacks for web page creation. There’s a lot of other useful tools out there that can be integrated with your RW-created sites.
Note: mdbook is free open source software; written in Rust. There’s a bit of a learning curve (no spaces in file names!) but not much. I have no relationship with the developer. And yes, I’d like to see improvements (a graphic interface would be nice; an easier way to update or add individual pages would be nice). Also, one plus is that you can export the whole directory to epub, which is something RW never figured out how to do (why??).
If you DM me I can send the key to enter the project so you see what I put together using RW and mdbook. There’s proprietary information otherwise I’d just post it here.
Finally, I didn’t even know mdbook had a search function. A ToC and a search function is a pretty good replacement for a real index, which so far lives in the analog world.
Your search database is now ready