Yup, theres gonna be bullet time. If you have played the specialists mod for half-life you already know how its gonna work. For those of you who are missing out on this awesome mod, ill lay it out.
Theres a pickup that gives you the ablity to turn on bullet time for a certain amount of time. Prolly around 5 to 10 seconds for TMU. It will slow down the entire map, and its the only real way to do bullet time in MP. If this has discouraged a few of you in thinking that the bullet time will be inconsistent or ruin gameplay, i urge you to buy half-life and play TS.
And yes, you'll most likely use some of the charachter's powers, even if you are differenct charachters, since we want it fully customizable. You can find combos that work out best for your type of gameplay (like if you want to be able to superman fly while you are ghost phasing, then max out those two powers).
I can answer questions faster if you ask them on the TMU forums, so everyone go sign up!
You also get to see screens that i am too lazy to showcase on other forums