upgrading from one version to another is not possible yet, unless someone will use ubuntu or another linux os.
each version is offering newer apps, newer techonolgies support and about cm6new the goal is to give more ICS/JB (android 4.0.x / 4.x.x) look to our android 2.2.2. ROM
About the installation you can use version 3, version 2 or version 1 installer to flash your V4 ROM, many people dealed problems with V4 installer, while others had no problems. maybe has to do with some libraries (dll) in their computer. So my advice for now is download any previous version as well as V4, then use previous versions installer and flash V4. it worked with others, i think wil work with you.
Trust me this image software is the most user friendly i know. Maybe you think that 20 steps in order to flash the ROM are many, but they are so many to explain any detail possible to non experienced users and avoid easy questions. advanced users can make these steps with closed eyes. other programs you suggested are not that much that user friendly meaing that you should reboot your phone twice and restrict you to 976 mb of ROM size. modern apps need much space and soon you must use linux to increase ROM size.
Me and other members here are open to smart suggestions. i am telling you again that if you suggest another method, better than the existing of course we will adopt it. as for me i will try next CM6NEW version to be published also on image form and if possible also o tar.gz form for use with o2droid autoinstaller
i do now know how experienced you are and how much time you can devote on this phone, but trust me everyone here started from quite low point and with much reading and testing they are able to help others. you are welcomed to do the same. no need to be a computer programmer to help