I would not be sure about the willingness of the CAA to issue a national licence at all (I understand that the legislation does allow it, though).
Renewing your licence or changing the details on your licence
If you hold a JAR licence, or a UK national licence containing EASA ratings, and you apply for it to be renewed or to change details such as your address, you will have to convert to an EASA licence and pay a conversion fee in addition to the fees for the rest of your application.
Regarding the medical issue, I'm sorry but you may say the same about any licence or rating. Just because my passenger pays for me to fly them, what relevance does me having to have a class one have on my competence? It's about duty of care and the more challenging nature of the act - single pilot, single engine IFR in IMC outside controlled airspace is the most challenging and, in my opinion (because I've done it and I'd rather not) risky flying you can do in the UK. Opinion is all I'm giving.
If the annex II/EASA comment was meant for me, of course EASA has nothing to do with annex II aircraft. As an owner of an annex II aircraft myself, I know that according to the LAA the RV6/7 are the only aircraft likely to be approved without individual inspection.
http://http://www.lightaircraftassociation.co.uk/engineering/TechnicalLeaflets/Operating%20An%20Aircraft/TL%202.28%20Night%20IFR%20assessment.pdf
If the person in the OP has access to a DC3 or 6, then fine, though I guess a type rating is in order.