I am a bit confused by your OP. Am i correct in assuming that your actual question is 'What font, colours, layout should i use for my book?'
In your own words you say it is a boring subject and written very dryly so i don't know how a colourful font and a decent margin is going to make it more interesting to read. If i took Stephen Hawkins 'a brief history of time' and used 'Indie flower' for the headings and 'Open Sans; for the body, and added some pictures of black holes here and there would it make the book any easier to follow?
Roald Dahl was a British novelist, short story writer, poet, screenwriter, and fighter pilot. His books have sold more than 250 million copies worldwide.
The Wiki https://en.wikipedia.org/wiki/Roald_Dahl doesn't really explain but his books are all illustrated in a particular style by quentin blake. If i picked up a book and saw the illustration i'd know if it was Quentin Blakes.
Yes i've changed diapers (nappies in UK language) since i was a kid as i have loads of younger Brothers and Sisters and more recently nephews and nieces. And i don't mean disposables i can fold a Square terry cloth nappy without a problem I've never had a problem with doing anything from Welding to Sewing, i don't care if it's considered a 'male' or 'female' job if it interests me i'll do it. If you see my other post recently you'll see i am taking 6 months shared parental leave to raise our first kid with my fiancee. I personally find gender specific books a bit off putting as it has certain implications whether you mean it or not and besides which you are cutting out ~50% of the population. But perhaps this is getting into too much specific gender politics. So i will say no more.
Back to the subject of an ebook...
If you are happy with your content as is then all you can do is ensure that you choose a font that implies trust but is also easy to read. Have a decent line height so it's easy to read. As with webpages have decent headings that you can skim read and get an idea of the page without having to read everything. Pull outs are also good if they have an important snippit of information.
I don't know much about e-books - are they still read on e-readers like the kindle? i.e. black and white. If so illustrations might stand out stronger on a b/w screen than a complicated screen grab.
I'd personally go for a website as content changes so quickly and you can dynamically provide content on user criteria, i updated from win 8.1 to win10 and then win 10.1 and the menu system changed each time, and that doesn't even include my other laptop on win7. Which would you screen shot?
If i was you i'd really look at the current market and see if there is actually a need or niche you can fill. I know books in general are up but does anyone read computer manuals? They may well do but for me i haven't picked up a book (or e-book) on computing in 10 years, everything i want to know i find online on websites as it is so much quicker to search for what i want to know at that specific point in time. I don't mean to be negative but you will be competing with some very established books and websites so you will need a hook of some sort to get noticed.