All of these tasks can be done for pennies by offshoring it to places like India. In fact most publishers have staff for proofreading, indexing, cover design etc entirely in India. My estimate is that you can recover the cost even if you sell as little as 100 copies.
I could hire someone if I was expecting to make a living from that, which I didn't. Unless, as I said, if I decided to do a lot of marketing for these books.
you can, but then need to know how to vet them, and ideally they can work together well (professionally, on time, etc). you're taking on more risks and/or more managerial work by doing it. certainly possible, but not without cost.
You can hire people to do all that -- if you expect to sell your self-published book, and still make more profits than with a publisher.