Sponix,
The incidents you list above, whilst certainly part of the communities TCAS learning process, are somewhat dated. To the best of my knowledge the issues raised have been addressed.
v7 TCAS compares the airdata presented to both transponders, not just the operating one, and flags 'Altitude fail' if they disagree, which disables the TCAS. So for erroneous altitude encoding to nail you, both ADCs have got to be in error by the same ammount, and become so at the same time. Highly unlikely.
As mentioned above, it appears the b757 manouevred first. From reports above, and the crews call to ATC, a descent was flown.
Someone else maintains that the t154 was also TCAS equipped.
If if it was equipped, (and on and serviceable), then they will have been receiving a 'Climb RA'. They descended. TCAS should still have been able to ressolve the situation by issuing a reversal to the b757 UNLESS it was pre version 7 (see my post above).
If it was not equipped, (or off) then they obviously followed their descent instruction. In this case, since it would not be a coordinated encounter, the b757 TCAS would be able to issue a reversal regardless of software state.
Now, pure speculation I admit, but lets say you are flying a non TCAS aircraft and you suddenly realise that ATC want you to descend urgently. As you commence your descent, you hear another aircraft saying 'TCAS Descent'. What goes through your mind?
CPB