According to valence bond theory, which kind of orbitals overlap to form the s−f bonds in sf6

To account for the hexavalency in SF6 one electron each from 3s and 3p orbitals is promoted to 3d orbitals as shown in fig.1.27(b). These six orbitals get hybridised to form six sp3d2hybrid orbitals. Each of these sp3d2 hybrid orbitals overlaps with 2p orbital of fluorine to form S-F bond. The answer is S(sp3d2)- F(p)

For cyclohexane compounds drawn in a chair conformation:   -axial bonds are vertical  -equatorial bonds are parallel to two bonds within the ring.  thus, as i assume the chair conformation is drawn:   -the x group is in an axial position, as are the five other vertical bonds.  -three axial bonds are on the top face of the ring  -the other three axial bonds are on the bottom face  the position of the second substituent on each ring carbon is equatorial.  gauche groups must be on an adjacent carbon such as carbon 6 and carbon 2, and also gauche groups are rotated by 60 degrees relative to each other.  drawing the newman projections for c1–c2 and c1–c6 aids in visualizing the groups that are gauche to the y group on c1.  click this link and watch some academic videos that may you more understand the topic