A:AnswerNo, these will not help your tinnitus. Maybe if you load an app on your phone that produces the noise, then these headphones would certainly reproduce the noise.
A:AnswerWhy would you need headphones that work with other headphones? These will pair with your device via Bluetooth and replace your other headphones. If you’re asking if both can be used at the same time by the same device, I guess that depends on the device, I think most won’t.
A:AnswerYes you could wear them while mowing the lawn and the noise cancelling will help however, these are "over the ear" style headphones and that may cause excessive moisture to build up when performing activities, same goes for wearing while woodworking.
A:AnswerThe bass isn’t the best but the sound sound quality is elite. If you don’t care about overall sound and want bass check out the Sony headphones. But you can tell the difference from Sony & Bose the Sony has bass but sloppy sound quality. Bose has a clear sound with medium bass.