Hey mate. I’ve never tested with visual composer. Why don’t you give it a try and see. Really depends on how the plugin structures their data. Also with regards to your Q about updating there are lots of options to customise your behaviour so it should be able to do what you need! 🙂
Is it your or any plugin have ability to load all data from other SUBsite? Just using one site for domain name.
I don’t understand the question and I guess the best way to find out is to try plugins. Quicker than waiting for a response on a forum! 🙂
Is it possible to duplicate, contact form 7, tablePress, other custom stuff?
Yes supports lots of custom stuff. I’ve not tested everything but as long as the plugin uses core WordPress database tables. Just try it mate. Too many questions man. Just give it a bash and see.