Mounted contacted in the flank by foot.

Under 7.7.2 the rules state that mounted in melee with foot that ended in a draw May retreat 1H.
Rule 7.7.3 states that a unit contact on its side, not flank, ‘slides’ across the face of its opponent if forced to retreat.

Can I retreat with cavalry if I have been contacted on the flank and the melee is a draw? I can see that under 5.13 I cannot disengage if contacted on the flank, but the option to retreat under 7.7.2 is not a disengagement, it is a melee outcome.

The rules seem assume that if I’m contacted on the flank the unit will be destroyed or simply stuck with with an enemy attached to my flank, unless I win the melee and flanking unit is forced to withdraw) in the event of a draw. Is this correct?

If I’m not disordered can I do an about face whilst in contact with a unit to my flank?

if you are contacted on the flank (not on the side) no, you cannot retreat. As you said or you are destroyed (melee lost) or you stay stuck (in case of draw).
And you can never make an about face while in melee/contact.