@eadah
Its usually best to have one simple question per post.
No you cannot have two inverters on a GX unless they are one system (if you want control over both) with one GX. Daisy chaining is possible in one ve bus system only.
This answers you other - you either have two sites on vrm with 2 gxs or one system on one GX
Are you split phasing or paralleling there is a big difference. (And yes you can do either or or even have only two of three phases configured). Important to know as it changes your physical wiring significantly and product choice.
Links in this post to documentation on the GX question