1) When will be supported RHEL 6.2 ?
It should just work.
2) Is it posible to add a existing vmdk file to an appliance definition ?
3) Is it posible to set the root password for my new appliance, how ?
os: password: yourpassword
4) Is it posible to deploy a created vmware appliance to an ESX host or VirtualCenter infraestructure ?
5) Depending on appliance type we need to create some specif users at the build phase, how to do that ?
Use post section to do this. There are different subsections for different platforms: http://boxgrinder.org/tutorials/appliance-definition/#post
6) How to create a new virtual disk of N GB in the appliance definition ?
The disk size is sum of the partitions sizes.
7) How to add virtual nnetwork interface ?, our appliance has two ethernet interfaces.
Only post section at this moment, but there is a plan to make this part of the appliance definition format.
8) I have built an appliance, I saw that a lot of packages were downloaded from an external site, is it posible to create an internal package repository in order to store RHEL packages ?
Use the repos section to use internal repos: http://boxgrinder.org/tutorials/appliance-definition/#repos