#1) With the 6-max HUD our approach has been to try to identify the useful information from the noise. There are a lot of stats out there which people have commonly used which can be "polluted". By this we mean that several distinct situations are being lumped together.
A good example of this is CBet out of position. This can include both times when villain opened under the gun and the button called and also blind vs blind. There are very different scenarios...and you will find our postflop stats have been filtered to split these kinda of things up.
So why RFI rather than the more traditional PFR, it is for the same reason. PFR includes all the times the villain has opened , the times they isolated a raiser and even when they 3bet, 4bet etc. All these are very different scenarios. RFI is a specific scenario, the % of times the villain opened when nobody else has come into the pot. It is the most common occurrence. You shouldn't find that RFI varies massively from PFR, but depending on the player there will be some difference to PFR. In terms of what you think is a "TAG", "NIT", etc, again we feel this is an outdated approach, instead you should be trying to identify ranges for different actions.
#2) We removed a lot of the limp info, because limping in 6-max games really isn't that common (perhaps aside from BvB), and normally only by the fish. Stats are only useful if you can get a decent sample size, and a fish who you don't have many hands on and you see limp / call 3 or 4 times it is difficult to really assess what that means.
However, we will have a look at your suggestions.
What this HUD, what we have found by the large amount of feedback we have given is that we can't please everybody. Thus, what we have tried to do is produce a HUD that provides a good solid platform, covering all the major situations. In the near future, we will be providing paid customers the ability to have a totally unlocked version, which they will then be able to customize however they wish. Furthermore, there will be opportunity to purchase add-ons, to better tailor the HUD your wishes.