Remy Hair Weave Questions?

I Want To Do A Sew In, Its My First Sew In & I Wanna Use Remy Hair & I Want It Too Look Full With A Nice Chinese Bang! So How Man Packs Should I Buy? & How Long Will The Sew In Last? & I Also Want My Bang Blonde But I Want The Rest Black So...Do I Buy A Pack Of A Different Color? HELP Lol