Custom API and reseller

Hello,

I have some trouble need help to improve our business better:

1. API called from WHMCS.com to WHMCS: currently we have multiple reseller using WHMCS system,
- Could i enable our WHMCS system allow they call to our system for auto register product ?
- Support their whmcs call to our system (whmcs) for auto register domain, then we will register direct with our registrar ?

2. Current with client group in WHMCS.com does not support discount for mutiple category product like hosting, VPS, dedicated server, etc... How to custom this on our system like:
- Reseller level 1: hosting 10%, VPS 5% and Dedicated 3%
- Reseller level 2: hosting 15%, VPS 8% and Dedicated 5%
- Reseller level 3: hosting 20%, VPS 15% and Dedicated 10%
and more....

For domain we could use base slab resseller but for product currently we can not setup this, does anyone know this ?

Thanks,