Walaikum As Salam and welcome !
Weather in Karachi will be 32 to 35 C in days and 21 to 23 C in nights.
Travel option, as already suggested .. Pak Business Express ..
Fare Rs 5000 Business class, including meals .. or budget class 4000 / smart class 3500 without meals / lcds.
Stay option, Shahrah-e-Faisal will be more comfortable as expo is concern,
visit their sites, hotelfaran.com.pk / hotelmehran.com