RE: how to test/boot a motherboard without a case
ya, you just make sure you use a table that is not metal. Basic wood is good.
Put the board down, plug everything in. If you have a spare switch/button, hook that to the power button pins on the mobo, otherwise use a screwdriver to connect the pins to start the system.
Don't use a jumper shunt because you don't want it connected all the time. You just want to touch them once and then let it be. If you use a jumper, it's like holding down the power button on your rig and it'll turn off in 5s or so.