Shopping store related question

Dear great helpful friends,
Yesterday I got a new domain name - ,so thinking to build a site .

Using multi site/pro site is it possible to build a shopping blog community on the main domain name and allow members to build their own store as sub domain/directory (also allow them to use their own domain name like wordpress) ?

If I also want to have a classified site ,is it okay to do that with a sub domain like ?Or a main domain is recommended if the shopping community is a part of the multi site network?It is better of sun domain is okay and there is a plugin to show listing/ads based on different areas of my country.

Pls also recommend some themes /plugins to accomplish what I want

Thanking you