There's a lot of info missing.
Note: Simultaneous power on could impact utility charges and not be good. 1 KW is a fair amount of power, so your talking 30 kW.
You failed to mention the mains voltage and even the order of magnitude for time. So, I'll take this as a "burn-in test" or on for a specific amount of time to see if problems exist.
You could consider monitoring current. Just a thought.
Easy way is a large contractor feeding a breaker box. AFCI's/GFCI's or combination are possible. Indicating breakers are possible with the right box.
If you want to roll your own, I'd suggest a smart relay because you can display say the time left for the test.
Your buttons could be start/stop and emergency off. Emergency off would kill the contactor. Tecor and IDEC and one manufacturer has smart relays. IDEC has a simulator.
So if the time was like 10 minutes, then the fanciness would not be necessary. But if the time was in hours, I would think more functionality would be needed.
e.g. An alarm as to when the test is complete.
Logging current over time is even more complex. Turning off bad ones is even more complex.
If you loook at your testing with the following additude:
1) What would I like it to do if i had all the money and time available?
2) What must it do?
3) What do I need now?
You may be able to design an upgradeable system.
What if ultimate was:
1) power up devices every 10s to minimize power spikes.
2) Power them down in the reverse order
3) Monitor and log current consumption of the devices and shut down errant ones.
4) Alarm if a device has to be dropped out.
5) Detect breaker trips either by a contact in the breaker or by current consumption.
6) Alarm a few minutes before test is over.
These are very different specs than what you started with