The Culverin Cannon is the special snowflake though, in that has a 360 targeting zone, but takes time to track to its target. So setting the initial rotation of the Culverin Cannon Module on the hull specifically determines how much more or less time it will take to track to a target depending on which angle the target enters combat.
Lock Range allows you "turn on" the range display in the Mega Build Mode without needing to keep the module selected or hovered over. This is really just meant to help you plan where your targeting / firing zones are going to overlap. Unlocking it will simply turn off the range display for that particular module. Locking or Unlocking Range has no direct impact in combat itself.
You can get a similar effect if you zoom out in your Mega view. If you click on a module while zoomed out, it will "turn on" the range display for that module. You can do this to multiple modules. Re-clicking the same module toggles it off.
Specials on the module only affect the standard weapons, unless the blueprint specifically states otherwise. We'll be introducing "Mega Specials" in the future that do affect the Mega Weapon, but those will be uniquely defined and represented via naming and/or new UI elements.
Standard weapons mounted on the module have the same range they always do unless the module stats specifically call out otherwise (such as Ballistic Range: +X%). The range of those weapons originate from the center of the equipped module, not the entire Mega Ship itself. So moving or placing the module in a particular slot on the hull does have some impact on where a standard weapon is able to reach. It doesn't matter which slot you equip the standard weapon to, they will all fire from the center of that module. The main thing that affects range relationship is the location of the module on the mega hull itself (in the same way that that a ship separated from the fleet off in the distance can still fire at things in its range).
No sonar or thermal at this time. There may be Mega Specials, Bridges, etc. that would provide either sonar or thermal in the future. However, that said, torpedoes currently cannot attack Mega Modules (it would be a little silly if they did). So really the only direct threat to a Mega Ship from submarines are those that can use surface / hybrid weapons (i.e. - missiles, scatterguns, etc). Submarines are a great way to try to counter standard fleets entering combat to fight against the Mega. So, if you are a standard fleet entering into Mega Combat, make sure you or your ally have sonar / thermal as part of their fleet composition.
It's definitely something we're considering. It would likely be an ability unique to a particular module or a Mega Special that could be equipped that would provide that capability. We will likely ease into powerful mechanics over time based on what we see players doing and where the Mega PvP meta is going at that time.
We're also working on additional new modules that are uniquely meant to battle against fleets more directly, which will also have some hiving potential in the future as well. So while standard weapons are important (they really are!), there will be plenty of options in the future to help handle standard fleets.
The retrofit bonuses from the Retrofit Lab should still be applied to the standard the weapons. The one thing that you will see though is that they will not have VXP, as modules do not gain VXP or have VXP levels. There are currently no plans to provide them with VXP as well. So while the retrofit bonuses should apply (since that's linked to the weapon itself), you'll see them shoot slower due to the absence of VXP.