1. I don't like that you're thinking about having a tech that shows you what class distant planets are. I think you should have a tech that shows you where planets are. Potentially even about what class planets are such as planet class up to 8 or potential 8-12. Such as right now we as a planet can tell planets are around stars and estimate it may be earthlike ect. But don't know for sure.
I agree with this. Matter of fact I'd like to push this a little more in specifying that it shouldn't be easy to detect planet classes. Leaving some of realism aside, I think it makes exploration more intense and rewarding not knowing where you specifically are venturing off to. An example of what I think would be enjoyable:
Planets that are 100 tiles away from your nearest sensor or more (sensor = anything you own; planet, starbase, ship, etc.) would give a very vague reading of Planet Class 5-15. This means the planet could be 6, 11, 14, etc. The thing here is you don't know what it is specifically, and there's a vast difference between a class 5 planet and a class 15 planet.
Planets that are 50 tiles away from nearest sensor or more give a less vague reading of something like Planet Class 8-14. You have a more specific reading so you can somewhat gauge what the planet will yield.
Planets that are 25 tiles away from your nearest sensor or more give a reading randomization of 3 (Planet Class 12-15), and Planets that are 10 tiles or less give you the correct reading.
I think something like this would still give the enjoyment and mystery of exploring space, while eliminating the RNG and bad luck that could occur when blind exploring (like in GalCiv 2).
EDIT: Also, maybe this could scale with game size to some extent.