The use of email is growing, although its avaliability is most widespread in Kathmandu (especially in Thamel and around the Boudha Stupa in Boudhanath) or Pokhara. However, Namche, in the the Everest region, has several internet cafes that use satellite connections, but the cost is more that US$2/min compared to 30 NRs in Kathmandu. Mail can be received at many guesthouses or at Everest Postal Care, opposite Fire & Ice on Tri Devi MAag. Phone calls are best made from any of the international phone offices in Kathmandu-- Voice over Internet (VOI) is usually 1-2 NRs/min.
Mero Mobile SIM cards can be purchased for 550NRs in Kathmandu and most major towns. You will need to bring a passport photo, fill in a form and have your passport and visa page photocopied. Try to buy the SIM card at a shop owned by the phone company as if you buy it from a corner shop it can take some time for the card to be activated, despite promises that it will be done in " a couple of hours" .
The standard Nepalese electrical outlet is a three-pronged triangle, but some have been retrofitted to accept US and European plugs. Simple adapters can be purchased inexpensively, around 80NRs, in Kathmandu to change the shape of the plug (but not the voltage of the electricity!); some have fuses built in.