It is a question for the scholars and I'm not one. So, my answer is not to be taken into account. I'm only trying to apply 'reasonable' thoughts to it and come to conclusion. When a scholar does answer, I will know how I faired. Islam is supposed to be simple, sometimes we over complicate things. So here goes
1) I'd say earn a living. It might even be an honest living.
2) time and effort expended.
3) there are costs incurred. If a whole chain of activities has costs, it cannot be denied that the 'service' aspects, like teaching also deserves payment at a fair rate. At least they can feed their families.
4) In this current times, we got to have cash.
5) people can always choose someone else.
On books, why not? Nobody is forcing anyone to buy. Plus the work of research compiling, arrangement, text design and printing, etc it can't be given away for free.

eace: