The answer is largely that there isn't a real answer (yet). This is because the algorithms used are not well known, and NMS has a smaller fanbase than it did at launch (for obvious reasons) so the wiki and number of fans researching the question are much smaller than they could have been.
What we do know is that all classes have a 38 slot maximum except Haulers, which can have up to 48. How these slots are allocated doesn't seem to tie to ship type much, since there are now multiple types of slot.
In order to determine the bonus caps, we would need to see the upper range permitted by the generator, and whether or not certain components it fetches from the internal database to construct a ship design play a role. The one thing that is obvious is that the minimum and maximum bonuses of any type are determined by class and purpose for the ship. C's lower limit on all of these is 0 for all stats except the stat closest related to the ship's purpose, which my observation has around 3%.
A large sample size with observations from multiple players would be required to determine the current stat limits in any procedural generation system without access to the algorithm. Hello Games has taken a largely "flip the generator on and see if it's playable" approach, so it's possible they aren't even entirely sure what these caps are or if anomalies can occur.