Responses as below in bold text:
does it have offline payment option?
By default, Vantage includes PayPal and manual/bank transfer payment options
do paid plans have automatic email reminders?
There are email reminders linked to listings which are automatically sent when the listing expires
do paid plan generate statistics?
There is nothing within the theme by default which accomidates stats, however you can purchase optional add-ons such as this and this for some stats information.
is the paid plan feature pre-set or I can define which fields will be made available based the selected plan? for example, can i create 2 (or more) plans as follows;
You create your own payment plans within Vantage, and the available settings can be seen here on the Vantage admin demo. You can also create custom forms which relate to categories if there are additional fields you wish to include on specific category listings only.
Thanks.