some thoughts.......you will certainly want to verify esp. for your particular state, etc. Don't know about the depreciation part.
We live in a community property state so property is in our joint A/B trust while we are both alive. At first death, property gets step up in basis and is put into either survivor trust (A) or residuary trust (B) or perhaps gets split between the two. If put into the A trust, it belongs to survivor who has power to dispose of it as he/she wishes so upon the 2nd death, it gets a second stepup.
However, if put into the B trust after the 1st death with the initial stepup,
when the 2nd death occurs, ownership is still with the irrevocable B trust so there is no 2nd stepup in basis.