Regarding the delegation and automation part of your question. It is possible for you to use a scheduler like Smarterqueue or Hootsuite, which ever suits your need, then get your FB Virtual assistant to upload all your articles, and posts etc (I use Smarterqueue!).

You assistant can also determine what articles, and posts did well and which didn’t, and amend accordingly, from the scheduler stats.

This would take care of the automation part, but wouldn’t you still want to engage with the people that respond to your posts? Particularly if you’re trying to build up a following, to sell your book and get clients. Maybe consider developing a social media strategy, if you haven't already, so you and you virtual assistant know what the aim is, otherwise you may end up just wasted your time, energy and money.