soldering, locations, why?, iPhone internal

If you are referring to parts you can replace/repair...only the mic/speaker on the dock assembly. It is possible to buy that unit all in one though so technically you don't need any soldering at all. Unless of course you are more interested in parts on the motherboard? in which case after you have removed the emi shield..everything including NAND etc is soldered.

Take a look at a guide for removing the logicboard..link to the right under the photo of the phone. You'll see the only tools required are a philips head screwdriver, spudger, suction cup. NO soldering iron.

The iphone 2g had a battery that required soldering to the logicboard, as do several ipod's.