By picking up creatures equal to their level and Fort save per critter picked up and fling them to a wall or other creature and deal damage to each other? Also if metakinetic feat as Empower Spell is used, is the x1.5 damage applied to all the affected targets [the creatures tossed and the target tossed on]?
No, these infusions can't be combined because they are both form infusions
As the Kineticist's Infusion ability describes:
Each time the kineticist uses one of her kinetic blast wild talents, she can apply up to one associated form infusion and up to one associated substance infusion.
Foe Throw and Many Throw are both form infusions, so you cannot use them both on a single kinetic blast - you must choose at most one of them to use for any given blast.
However, if you want to be able to throw a lot of foes in one turn, you can use the Kineticist's Metakinesis - the 13th level option can quicken the kinetic blast to use it as a swift action, and the 17th level option allows you to produce two blasts with a single action. Combined, those would allow you to use a swift double blast and a standard action double blast to target up four different creatures and throw them at up to four more creatures, albeit you would have to have gathered power on the turn prior and make use of your Internal Buffer in order to able to get through that much burn in a single round.