General Advice...
Hero Points. You should be handing out hero points like candy. The more you hand out the hero points, the more your players will use them, and the more out of the ordinary stuff will happen.
This can make a huge difference in how your games run. I've played in games under two different game masters (as well as running myself), and the difference in how often they give out hero points is gigantic. The game with fewer hero points has actions like, "I blast him with my power." Whereas the game with more frequent hero points often has things like, "I burn a hero point and alternate power my water blast to nullify the bad guy's fire blast before it fries the bystanders."
Problem Powers. There have only been a couple of powers that I've seen as problem powers (and I've seen a large variety of powers). Those are... Duplication, Disintegrate (or, really, any trait drain combined with something else), Mental Blast with ESP (or, really, any Perception Range attack combined with a supersensory power), Time Travel (or Dimensional Travel or the temporal senses) depending on the campaign.
To some extent Teleport, at the really high ranks can get out of hand.
Powers that are configurable (i.e. Variable Powers) or that have a lot of Alternate Powers can be problematic, especially if you have someone who takes a long time in decision-making anyway. In general, I'd probably limit any one power to having four alternate powers (for a total of five abilities out of a single pool of power points). And this is just to keep the decision time down for those players that hem and haw about things a lot.
Also, moving powers to smaller action types should be discouraged. Anything that would normally be considered an attack should always be a Standard action or greater. Anything that would normally grant movement should be a Move action or greater, and so on. Also, changing forms should probably not be allowed as a Reaction.
As for PL. I generally like to start at PL 8 or 9, and use a higher power point total. But I've played in Games from PL 6 to PL 12, and they were all pretty smooth.
Edit: Oh... And some advice for your players, too... When you are making your characters, make sure that you fill out your caps on attack and damage, defense and toughness, and your saves (in some cases, it could help the flavor of the campaign if every character had one non-optimal save). if you are not filling out your caps, or coming at least close to doing so, you are going to have a difficult time during play.