1

The northern beaches and Iquitos are totally different worlds.
For beaches in northern Piura and Tumbes departamentos you could check www.vivamancora.com which if I'm not wrong is made by a Chilean.
There are many beaches along the northern coast, some more popular than others with Mancora being the busiest and probably ugliest chaotic architecture.

To get to Iquitos the easiest way would be to fly from Lima.
www.starperu.com has return flights for 185 USD (Peruvian Airlines & Lan Peru also have flights to Iquitos but these are much more expensive) but you could travel by boat from Tarapoto or Pucallpa.
Here's a good link about jungle cities in northern Peru: http://www.viajeros.com/foros/peru/aaa-iquitos-tarapoto-o-pucallpa or do a search in google with the words barco, Pucallpa & Iquitos.

2

I am in Mancora now, heading to Tarapoto in two days, and then onto Yurimaugas and to Iquitos by boat. Let me know, I wouldnt mind having a travel buddy.