yes u should go for that meeting, ure lucky u got appointment v soon unlike others, second u need nothing to carry with u, they will ask u some questions which u have to answer, try to convince them. third yes u can convert visit visa to family visa once u get ure appication accepted. when the status change at MOI site to ready to print, go to jawazat pay 200 QR for the visa and 500 to convert visit visa to residence visa. then again to medical and to finger print to get her ID. khalas.
good luck for the meeting.