-I think that detailed surface scanner should be limiter to work only from planets/stellar body's orbit. And credit gain from it should be drastically increased. So you would need to get to planet, scan it from orbit and then you would get full scan.
I agree with you regarding system view and initial scan with Discovery scanner. But they have to balance it with better rewards for more detailed scanning.
shootable probes is nice idea; but they should be limited to "shooting" out from orbit only, and should be used in tandem with detailed surface scanner. Price of individual probe should be also high, abut payback from good probe scan should also be high. But, you could also very easily lose money on probes if you don't pay attention where and when you use them, so detailed surface scan would be a must before using probe, because then you would get more detailed data about that planet, and decide if you should use probe or not. Amount of probes you can carry would be affected by ships size, so better class probe modules would have bigger capacity (and each probe should have mass of 1t like one cargo unity, so more probes = less jump range)
at least one of ships should be specialized for exploration with way bigger jump range, but with no weapons hard points (or very few 1-2, and low tier), but should have long jump range (40 LY+ max), limited internal components so that you can fit exploration components, but would limit potential cargo capacity (max, let's say 32-64t) and suggested probe capacity. Maneuverability should be also poor, but should have good speed (since you have poor or none weapons, you can at least outrun pirates). So, beside exploration, this ship would also be good for rare goods trading. And price range should be between 1 and 5 million.
one other interesting thing that could open up potential of players collaborating when exploring, would be option to buy fuel, probes, ammo and other consumables as cargo and be able to transfer exploration data to other players, so that you can for example have ship fitted for exploring, and your friend for transport.. So he could resupply you with probes and with fuel if you get stuck without fuel (or if you didn't fit fuel scoop because you needed spot for some other modules). So you friend would fill up fuel tanks with fuel scoop, get back to you, dump those fuel tanks, you collected them, refuel and dump them back out for him to fill them up again. And when you are done with scanning, you transfer data to him, he runs to closest outpost and sells data, and both of you get payed; you regular price and he anywhere from 5 - 100% of your price, depending on how much he participate (this part should be very good balanced, to make it fair)