Hi - yes - I definitely recommend sharebird's resources. I also love a few books on positioning. First the classic book here is from Al Ries and Jack Trout and it's called "Positioning: The Battle for your Mind." I also recommend "Obviously Awesome: How to Nail Product Positioning so Customers Get It, Buy It, Love It" by April Dunford
More than one persona can definitely make sense. It just depends on the business. Ideally you want to have one persona per “target audience”. The balance is having enough to create coverage across the segment(s) that are strategically valuable to the business, and not too many that they become information overload and are not actionable.
Analysts will not endorse any vendor directly. Your goal with AR is to help shape their POV about the market, especially if this is a new category and ultimately get well positioned on MQs and Wave reports. Shaping their POV means showing analysts how customers are getting value from this new type of solution and what critical capabilities that are required to be successful. Do this by building a personal relationship with the analysts, sharing insights, connecting them with your customers, and keeping them updated about your roadmap and product innovation.