Add warm water to the gel as required to dilute.
Yes. It can be used on fondant, whipped/fresh cream, buttercream, ganache, chocolate, modelling chocolate.
Not required to refrigerate for storage. But can be refrigerated if on cakes. It will set while in fridge.
No. It will set like jelly but wontget hard like royal icing.
Only for writing and designing. It cannot be substituted for Royal Icing to create 2D structures or stringwork.