Purchase of shares in a pvt company

Check article for transfer of shares in the AOA of the Company

Market or fair value should be the transfer amount further article restricts the transfer of share to outsider

Absolutely ( Unless otherwise any restriction in AOA), In a private company Existing shareholders have right of pre-emption and it will always be offered to existing shareholder(s) by selling shareholder ( Generally Selling shareholder will shows his intention to Board and The Price will be determined by CA & if accepted board will intimate to existing shareholders about Price & quantum of shares available to acquire, if no-one is interested within the time stipulated then selling shareholder is free it to offer to outsider, once board took a note of no quotes received or received at lesser price)

As per your second query, In pvt companies directors are also shareholder, so in a capacity of shareholder they can acquire shares, If there is a director who is not a shareholder, then as an extended compliance you can call EGM and get approval, if it's new allotment to director then will fall as pvt placement (u/s42), so already shareholders approval will be required .

Disclaimer - For educational purpose only ..