Starfarers of Catan game mechanics
You could try it. It probably wouldn't fundamentally ruin the game. It would reduce the randomness. Depending on your group's preferences that could be a good or bad thing. Overall the event cards are more or less breakeven, so removing them wouldn't slow the game down much, and would reduce the reading and decisions encountered in the game, which would probably speed it up.

Normally the black ball sets the base speed to 3 (regardless of what the other ball is); that makes the average base speed 3.5. The second change you propose, to use 2 for the black ball, would raise the average base speed to 4. Not a huge difference and again, unlikely to break the game. And faster movement would get ships to colonizable planets faster.

Cannons would indeed lower in importance, and they're arguably already a lower priority than other uses.