I think your point 2 confirms this with regarding planning purposes, to use CMV when no RVR is presented or available.
When no RVR is reported, you will use CMV to know what this number would be in RVR.
The table tells you what conditions apply for RVR vs CMV, and must be used for planning purpose.
All other circumstances besides take off, this means your approach etc.
Normally you will need to concentrate about Visual, Non Precision and Cat 1, as your normal approaches.
If you during flight get Visibility given, you will need to convert it to RVR to know if you are above your minima.
Example single pilot Cat 1 approach requires 800m RVR, if you recieve a met report in your TAF where your visibility is 600m, then you need to use the table to see if you will be legal. Normally RVR will be given in METAR and ATIS, however you might be interested to know how it is going to be, as the TAF is a forecast, and the METAR is actual conditions, which might not require and RVR report at current time.
If your TV says that during your approach time, visibility will be 600m, you need to use this for your planning, and use the CMV to get your RVR calculations correct. If your approach has HI Int. light in night, you will multiplie the 600 with 2 and have an RVR of 1200m, however if you doing approach at daylight, and no Hi Int. approach lights available you can only use the factor 1, so your RVR will be 600 m, so you will not be legal to start the approach after FAP.
Now if in Daylight with Hi Int. app light, factor will be 1.5, this means 900m RVR, so you could legally plan for that approach.
Note however that a METAR with a TREND in the end, will take priority ahead of any forecast in the TAF, in that first 2 hour period which the TREND is valid for.
You have to think a little of the situations when you would need to use the conversion, the table is given in JAR OPS, so that you know how to convert any Visibility distances given to useful RVR measures. If you was not going to use it, it would be useless for them to put the table in the Ops. Also it specifies when to NOT use it, so besides this you can use it all the time, unless you have RVR, but you will most likely never have the RVR during planning part of flight (as only in METAR and ATIS)