True-bypass is a good answer only to the function 1. If the effect has poor characteristics (e.g. low-cost buffers), it's the worst answer to functions 2 and 3.
As for function 4 (remote switching), true-bypass can be used, provided the designer has included a costly relay system in the device.
All in all - and that's my own experience speaking, rather than a technical approach - true-bypass is truly bad, except in one very specific context:
When you want to merge an excellent tube amp with other devices, especially solid-state gear, the slightest addition to the all-tubes circuits will of course alter the sound.
Alter doesn't mean degrade: the sound is just different. If you really want to keep intact the pure sound of a stand-alone quality tube-amp, and use in the same rig other devices, the only solution is to install remote-controled relay true-bypass systems in your rig.
It's costly, and usually requires custom design if you take into account the fact that each set-up is unique.