Hello,
if you calculated succesfully your H-inf controller with state-space representation (as you mentioned you will get 4 part called a,b,c,d) you can convert it to laplace form with below code.
[Ak Bk Ck Dk]=unpck(K_hin);
K_ss=ss(Ak,Bk,Ck,Dk);
tf(K_ss);
About the weight, this is very critical question because those weights are key to design of robust control. So without weights we can not say the final controller will be robust. I prefer to you get some more information about the robust theory for example on Skogestad book.
