What Are PIA Weight Limits/ Need help with seats.?

OK were going to chicago the 21 from karachi, PK 794 and i needed to know the weight limits for checked, carry on, and hand bag. Were having a little confusion, We heard its 23kg checked, 8kg handcarry, dont know about hand bag, for the hand bag can we use a sports bag? what are the limits/ size/weight for hand bag?? Also i cant seem to find our planes flight seat arrangments on flight guru what is economy is it 3 seats then 4 then 3? or 2 seats then 5 seats then 2 seats?? Also we booked from a ticket agent, and he never gave us our seats? he ssays well get them during boarding but were going as a famiyl and i would like it if you as a family could sit together we have 5. Example if its the 3 seats 4 seats 3, arrangment then if we could get the 3 seats but front behind eachother so, example 3 sit in row 23 right side, and 2 sit in row 24 right side, or if we could get the 5 seats if its the 5 seats in the middle?? Please and thanks