1. The PTK is generated as follows: $$\mathrm{PTK} \gets \operatorname{\mathrm{PRF-X}(PMK, ``pairwise \ key \ expansion", \\ min(AA, SPA) || max(AA,SPA)|| \\ min(ANonce, SNonce) || max(ANonce, SNonce)) } $$ where $\operatorname{\mathrm{PRF-X}}$ for $X = 128,192,256,384,512$ is defined as follows:

   PRF-X(K,A,B): for i = 0 to (X + 159) / 160: Z = Z || HMAC-SHA1(K, A || 0 || B || i) return LeftBits(Z,0,X)

The following answers are taken directly from the 802.11 standard (2012 version).

1. The PTK is generated as follows: $$\mathrm{PTK} \gets \operatorname{\mathrm{PRF-X}(PMK, ``pairwise \ key \ expansion", \\ min(AA, SPA) || max(AA,SPA)|| \\ min(ANonce, SNonce) || max(ANonce, SNonce)) } $$ where $\mathrm{AA}$ and $\mathrm{SPA}$ are the MAC addresses of the Authenticator and Supplicant, respectively. The pseudorandom function $\operatorname{\mathrm{PRF-X}}$ is defined as follows for $X = 128,192,256,384,512$:

    PRF-X(K,A,B):
       for i = 0 to (X + 159) / 160:
           Z = Z || HMAC-SHA1(K, A || 0 || B || i)
       return LeftBits(Z,0,X)
   

2. The MICs are computed using either HMAC-SHA1-128 or AES-CMAC-128 (which one to use is negotiated during the handshake).

3. The GTK is simply chosen at random by the AP.