SSRS Custom Delivery Extension - newbie questions

Hi Folks

I'm about 95% done on building an SSRS Custom Delivery Extension (in terms of code).

I'm in a common/shared development environment where I'd like to have myself not being a disruption to my group.

Two questions I have:

1. Does a SSRS Custom Delivery Extension circumvent/preempt the standard ReportingServicesEmailDeliveryProvider? (I'm running in a multi-web environment and only ONE web site actually needs to use this extension.)

2. I have yet to figure out how to call this provider explicitly/programmatically, for a single application, based on individual client and report (my environment is VS2012, VB/ASP.NET.

Thanks

Rob