You should have knowledge of whmcs cpanel software , resellerclub domain api .
1. Admin control setup with hostnine and reseller club domain api.
2. Automactic billing setup and domain activate (from reseller club) after payment if choosed paypal other wise pending if he choose bank transfer
3. Two sites to be display one in usd and inr ( so the usd can have other languages too , not a google translator! )
4. whmsc shopping cart changes
5. domain api intergration on same page of hosting as well as add cart system
7. shopping card should be displayed and setup properly of whmsc.
8. domain and hosting should be control or changed private dns address with one client login id only
Hope you understand reseller domain api + hostnine +whmsc
for more details and about site please send me private message.