Re: Create form of model-type using model manager ?
Model Manager does not support to configure a model-type form for document creation, though it will implicitly create a model-type form for search if I remember correctly.
Model Manager is a convenience feature that was not really designed to be extendable / customisable. Though it can be technically extended / customised via the typical Aikau or Java/Spring approaches, there are no officially supported extension points provided by this feature. It has many severe limitations in functionality (not just the lack of a create content form) and I typically recommend it only be used for prototyping models in dev/test environments or demos, but never real production-grade solutions. Standard extension development approaches should be taken to build regular extension module(s) as JAR or AMP.