I think using steam for power might make the game too steampunk. It's a slippery slope, you add a simple steam hammer and suddenly it's all rusty pipes and zeppelins and steam-powered robots. Some kind of natural and artificial geysers might be nice, though. I can see dwarves harnessing geothermal energy for steam traps, central heating and pretty steam clouds in the dining hall, but going too much beyond that might be thematically inappropriate. I disagree with mechanised training dummies for the same reason.
Logic gates, on the other hand, are simple. If you can build an automated crossbow trap, you should be able to make it trigger or not trigger based on any number of conditions. They obviously weren't called logic gates in the fifteenth century, but that doesn't mean clocksmiths couldn't make them.
I agree with the sentiment expressed by Soadreqm, steam power is out along with anything that smacks of 'robots' or 'automatons'. I would be open to gunpowder as an expensive Alchemist created material along with primitive cannons but nothing beyond that.
As for the specifics heres a quick boolean opinion
Class A: New Systems
Steam - No
Electricity - No
Conservation of Energy (No perpetual motion machines) - Yes
Gravity damage (ability to drop things on people for damage) -Yes
Moving Objects and Inertia (Giant Rolling Boulder) - Yes
Tech Tree - No
Allow dwarves to build anvils without an anvil, picks without first mining.
Assign Techs by Civ, Research new ones over time.
Class B: Power Providers
Steam Turbine - No
Kinetic Battery (Hanging Stone) - No
Chemical Battery -No
Capstan (Animal Power) - Yes
Furnace/Incinerator - No
Archemides Mirror - No
Class C: Power Transfers
Pipes (For liquids and gasses) - Yes
Waterproof Axle Section - No
Class D: Power Users
Heavy Doors (require power to move) - Yes
Clocks - Yes
Bells - Yes
Rock Grinders - No
Workshops (Increased efficiency?) - No
Fans - No
Scissors Lifts (Really Mechanical Lifts of any sort) - Yes
Power Drills (Hydraulic, multisquare, digging straight down) - No
Dwarf Trainers (Sparring Partners or exercise machines) - No
Class E: Flow Controllers
Vertical Pump - Yes
Spiggot - Yes
Pressure Equalizer - No
Internal (pipe) Pump - No
Misters (Water Pressure = Mist) - No
Dams and other depth controls. - No
Class F: Existing Constructions Improvements
Pressure Plates - Yes
Make them not traps
Make them weight sensitive (rather than creature size)
Weapon Traps - Yes
Make them take up space (Put them in walls, floor, ceilings)
Make them require power
Give Ranged Weapon Traps range
Allow some traps to hit more than one square (Large Serrated disk)
Reduce maximum weapons in one trap (to 3)
Stone Traps - Yes
Make them require ceiling
Big stone trap (blocks path)
Drawbridge - Yes
Make non-instantaneous
Mechanisms - Yes
Make out of Metal
Make ONLY out of Metal
Levers - Yes
Ability to close a door and open a window with one switch
Traps - Yes
Separate Trigger from Trap in most/some cases
Separate Power from Trap in most/some cases