dnd-4esummoning
In the PHB1, summoned creatures are very clearly defined in the power descriptions that summon them. In the PHB2, particularly the Invoker powers, I find many summons such as Angel of Fire that do not define all of a summoned creature's attributes, or even how long it persists.
Where can I find this information? Have these powers been errata'd?
The summoned creature is a valid target of such effects however it has no inherent ability to use basic attacks so the end result is not favorable for you.
The attacks allowed to each summoned creature are as listed for each power. Currently I am aware of none that grant basic attacks. Summoned creatures are not granted any basic attacks by default. Basic attacks are indicated like this 
for Melee basic attacks and like this 
for Ranged basic attacks.
The Rules Compendium states on p120 in the Commanding the Creature section that, "The Summoned Creature has no actions of its own...The Summoning power determines the special commands that the summoned creature can receive and gives an action type for each command."
Compare Basic Attacks to Opportunity Attacks.
Opportunity Attacks, like Basic Attacks (as Simon notes) are also granted to all creatures (RC p246). There are many summoned creatures that are explicitly granted Opportunity attacks. See Phantasmist Stalker for one example, its Opportunity Attack is identical to its normal attack.
From this you can infer that Summoned Creatures do not have Opportunity Attacks by default. Hence they should have no Basic Attacks as well.
The Knight is found in Heroes of the Fallen Lands, or I linked to the DDI description if you have access to that.
It is a fighter variant. This means you can replace Knight powers with Fighter powers of the same (or lower) level.
Best Answer
Summons is now its own effect type with general rules surrounding it.
Pg 221 has the info on Summons that you are looking for in the Player's Handbook 2
Pg 218 has the same info in the Player's Handbook 3