Make sure the SEO guy gives you reports each month showing progress in the rankings

I think it is good to either have a good reserve for slow months or having some sort of side job in the beginning. Some are not able to work on side jobs so people may opt to have reserves and have some sort of pipeline of revenue coming in before going full time.

You are right. Any updates on site will require you to think about SEO so there is no lost traffic

here is a QA wordpress you can use http://www.designwall.com/wordpress/plugins/dw-question-answer/

Also this is good seo plugin as well https://yoast.com/wordpress/plugins/seo/