I like the idea of adding more variety to the weapons available, my USR thread is basically about that. Boil down the special rules into USRs, ships that have them now keep them. But add options for a few ships to gain access to some of the USR's as well. The variety of things you bring up would make good selections as well.
Maybe universally lances could be changed in ship profiles to Lance (N+) (C) where N is the number you have to roll equal or above to hit with the lance. C, if a number, is what you need to roll for a critical.
Universally weapon batteries could be changed to.... Battery (A or N+) (C) If A, you roll to hit against armor, if N+ you need that number to hit (like with bombardment), C is the number to critical.
Then of course, if we add in the number required to roll a critical to the weapon profile, we could add critical modifiers to each ship. Most ships would not have a modifier, maybe eldar ships would have a +1 modifier making them easier to cause criticals against.
Then you have other tules you can tack on, like the DE phantom lance rule could be boiled into a USR you could add to lances or batteries, or even torpedoes as well, rolling a 6 causes 2 hits, any other roll that hits causes 1 hit.
Hmm... thumbs up for your thread, you gave me a lot of things to think about for things to do