Re: Summon: Am I missing Something Here...?
It seems as though you may be somewhat discounting some parts of the power description:
"The GM may refuse to allow a character to Summon a being the GM considers too powerful or potentially unbalancing." and "The GM must approve all Summon powers and Summoned beings after he examines them for campaign suitability and balance." -- This is the overarching point that makes Summoning not an unbalancing power: it's the responsibility of the GM to say "nope, sorry, that's cheeseball. If you want a slavishly devoted robot, you can build it on up to 50 points, and you can only have a maximum of four of them."
"Characters should not be allowed to Summon hordes of powerful, easily-controlled creatures unless there are equally powerful restrictions on this ability." -- directly addressing the "I can raise dozens of powerful zombies in just moments!" problem.
"If the GM doesn't want to spend the time and effort to build a Summoned being..." -- the implication, which I think is clearly stated in an earlier edition of the rules (maybe 4th?), is that the players don't get to design the Summoned beings. That is something that the GM does. So a good defense against a cheeseball Summoning power is to not build Summoned beings that fit the cheeseball profile.
So my advice, based on what you've said about how unbalancing Summoning is likely to be in your campaign, is to simply ratchet up the diligence with which you apply the "examines them for campaign suitability and balance" clause, and simply not allow Summoning powers unless you are entirely comfortable with them.
The same thing applies (as others have probably already observed) to Multiform, Duplication, VPPs, and really everything else in the rulebook. If you're not comfortable that a particular power mechanic will fit in well with the kind of campaign you have in mind, disallow it.
That's also at the discretion of the GM. The only rule is "The GM decides what constitutes a 'task'." There is also a guidleline on 6E1 289: "For combat, each Phase of fighting usually equals one task. For ordinary house-hold chores, carrying loads, or pulling wagons, each day of service normally qualifies as one task." But the only rule is: "The GM decides what constitutes a 'task'."
Hope this helps!