I recently wrote up a description of of a combat over on the HERO forums.
Here's the link:
http://www.herogames.com/forums/topic/89024-sample-fight/
Which might not work. I'm famous (not really) for never getting my links to work. In which case copy and paste are your friends.
As for the long process of character design: Hero Designer is AWESOME. Really. It handles both 5th and 6th edition rules and can handle anything from fantasy, sci-fi, supers whatever.
I'm not sure how Multiform works in 6th; IIRC it has changed from 5th edition (which is what I run.)
Multipowers aren't too bad (especially with HERO Designer.)
Design each power in the Multipower separately.
Work out which one costs the most.
The highest cost is the cost you want to pay for you MP. This is because the Point Pool for the MP must be at least as many points as any power within the MP. So say your building a Multigun. It's got 3 settings (slots in HERO speak): Kill, Stun and Sniper. For sake of argument let's say Kill and Stun slot cost 50 points each and the Sniper slot costs 60. Your MP must be built on 60 points.
Next each slot within the MP costs points = 1/10th* of the cost of the power within the slot. (In above example the slots cost 5; 5 & 6 respectively.)
As far as Power Limitations go they can be placed on the base MP Point Pool or the cost of the slots or both.
And once more I really really recommend HERo Designer.
*There is the option for slots at 1/5th cost that allow you to change the amount of the Pool Points you can use in each slot rather than using a predefined amount. This does start to get complicated and I don't have time to explain in detail here sorry.
Cheers. and Happy HEROing.