Returning to the original question.
Assuming that by 'ICAO' licence (ICAO don't issue licences) you really mean a UK national licence, the rules for conversion to a Part-FCL licence are at Annex II to the Implementing Regulation. This legislation has, of course, not yet been presented to the EU Parliament and so it is possible that it may be amended before finally being accepted (or rejected). According to the current draft, a national PPL issued by an EU member state may be converted to the Part-FCL equivalent by demonstrating adequate knowledge of the relevant parts of Part-OPS and Part-FCL, language proficiency in accordance with FCL.055 and use of radio navigation aids (presumably by means of some kind of proficiency check).
There are no requirements for the transfer of night or class ratings - if your national licence includes night and MEP privileges, these will be automatically transferred to the Part-FCL licence.
The FRTOL is a requirement of the UK Wireless Telegraphy Act and, therefore, unaffected by EASA. It is assumed that the UK CAA will continue to issue this licence on behalf of OFCOM.
There is, at present, no equivalent to the IMC rating under Part-FCL although work is going on behind the scenes in an attempt to obtain some sort of credt for existing holders. Whether this work will be successful and what, if any, credit will result remains to be seen.
The UK CAA is naturally keen for all national licence holders to convert to a JAA licence prior to the coming into force of the new legislation as this is, for them, the easiest option. Whilst it is possible to convert direct from a national licence to the Part-FCL equivalent, it will probably be less hassle to do so via a JAA licence.