NCS can interwork with IOS XE today (e.g. There is NED support)
2.Adding Conf D to a platform (such as ME1200 or ME4600) is a engineering effort for the platform team rather than a Conf D engineering effort. Conf D is essentially a SW product which the product team integrates their code with via API´s. Decision to leverage Conf D is therefore a PM / Engineering decision on the platform team (e.g. Build vs. Buy)
3.Conf D is a proven technology (75+ customers), comes with built in characteristics that saves development time and effort + offer operational predictability (transactions, rollback, automation, feature consistency by virtue of auto rendered northbound interfaces etc.). In your case it sounds like your starting point is to analyse Conf D as a vehicle to get Netconf/YANG support on two already shipping products. In such a case you essentially have to decide whether you are better off rewriting the existing code to work with Conf D (giving access to the Conf D goodies) or whether you are better of adding Netconf/YANG natively.
4.The way to determine whether your use case is supported is by taking your config file (sh running or equivalent) and comparing it with the NCS YANG representation of your product. We have customers doing a variety Carrier Ethernet wire services but I would recommend an analysis of your desired config file. Adding features and functionality to a NED supported platform is typically not that complicated, it is predominantly a matter of engineering resource prioritisation. The process for getting things done is customer driven and thus you need to engage with the NCS overlay sales team to register your opportunity. Similar to Tony, the NCS sales team reports to Hal Gurley. While NED work is in some cases performed by 3rd parties such as product teams it is done in concert with Tail-f engineering (following Tail-f quality assurance process) to ensure the quality of implementation and integrity of the orchestration system.
5.NCS supports a broad set of platforms and we have yet to find a networking platform that we can not support using the NED approach. That said, can you be a bit more specific?