As this others have said, this is really interesting. In answer to your questions:
1/2. I would use features of dvd if I had to. I don’t come across many children and haven’t had much differences of opinion with NHS colleagues. I have been on a course though which suggests that if DVD is suspected you should always treat as inconsistent speech disorder and use core vocabulary in the first instance. Thinking about a child that I’m currently working with this wouldn’t have worked so whilst I see how the 2 can be confused I wouldn’t always agree with following this recommendation.
3. I use both the DEAP and Nuffield but lean to Nuffield with suspected DVD. I’ve just completed PROMPT level 1 online and hoping to incorporate this into assessment
4. I want to say fairly confident but there are always times when I’m not sure!
5. Nuffield (loosely as the words aren’t always relevant), just trained in PROMPT but yet to use, cued articulation/jolly phonics depending on what the child prefers, semantic/gestural cueing. Also I’ve been looking into DTTC (dynamic temporal tactile cueing). Known in the states. I’ve been using a fair bit of it already but reading about the approach has helped me fine tune therapy.
6. I’ve read Nuffield and DTTC are evidence based but not sure about other approaches.