Roof deck questions

Hello, I’m trying to create a deck on the roof of a 1 story extension. If I’m not mistaken, the railing has to be 42″ to be up to code and i need to have 3′ of non-combustible material from the property line. Since Im the only one with an extension and there isn’t a structure next to the the extension, do I still need to observe the 3′ property line requirement? As for decking material itself – has anyone used pavers and can they just sit on top of the roof without being secured to teh joists or subfloor (I don’t want to penetrate the membrane if possible). Also, I had the roof redone recently and they put in fibreglass insulation boards under the felt and membrane. Can I put pavers or Ikea decking tiles on the surface or does it need to be hard, ie plywood or concrete? Thanks very much!