yes u can book seats from Karachi on provided number ... yesterday i also book it from Karachi for end on June 2010
last year i visited naran and stay at new sesal hotel which is very clean and comfortable for families and payed 1200 per night but as june and july are peak season u might get room in 1500 +
jeep fare for saif-ul-maluk are fixed so u don't have to worry about it ... last year i payed RS 1200 for jeep