The Steiner eOptics Laser Devices Dual Beam Aiming Laser is not compatible with the Surefire Dual Switch.
Yes, the Steiner eOptics DBAL-D2 Green Laser Device can be mounted at the 12 O'clock position and clear a front sight block/post.
The lever is tucked in under the body of the laser unit..... would be quite unusual for it to become detached. You can also add a zip tie for secondary retention but I don;t believe it is necessary.
There is a visible laser, but the IR illuminator will not be visible to the naked eye.
Unfortunately, Steiner does not offer height dimensions for the DBAL-D2. However, from the setup you a planning to use this with, you should be able to see over this laser without an issue. Especially with an ACOG or any magnified optic, even if the laser is visible in the lower 1/3 portion of the optic, you will naturally keep it out of focus while looking at your reticle.
The name and description, "DBAL-D2" is listed on this page multiple times in multiple locations. The MPN: 9001 and MPN: 9002 specifically correspond to the DBAL-D2 in black and desert sand from Steiner.