the system i would like to deploy inside the openstack instance is a management system. how user data or heat can be used to proceed this deployment ?

I don’t know your application. Read the Heat documentation, e.g. https://docs.openstack.org/heat/lates.... User data is based on cloud-init and is well integrated with Heat.

how can i access a deployed system/application if i'am using networking option 1 without a floating ip ?

Through the instance’s IP. The instance is connected to a provider network, i.e. a Neutron network that corresponds to a network in the datacenter.