ICAO Doc 4444
4.5.7.5 READBACK OF CLEARANCES

4.5.7.5.1 The flight crew shall read back to the air traffic controller safety-related parts of ATC clearances and instructions which are transmitted by voice. The following items shall always be read back:

a) ATC route clearances;
b) clearances and instructions to enter, land on, take off from, hold short of, cross, taxi and backtrack on any runway; and
c) runway-in-use, altimeter settings, SSR codes, level instructions, heading and speed instructions and, whether issued by the controller or contained in automatic terminal information service (ATIS) broadcasts, transition levels.

As for the statements:

The flight crew shall read back to the air traffic controller safety-related parts of ATC clearances and instructions which are transmitted by voice. ---> CORRECT. This is the basic principle defined in ICAO Doc 4444. Readback is mandatory for the parts related to safety of flight to ensure that the flight crew has correctly understood and is able to comply with the critical instruction or clearance, which prevents misunderstandings that could lead to an incident or accident.

ATC route clearances, runway-in-use, altimeter settings and surface wind should always be read back. ---> INCORRECT. ICAO Doc 4444 provides a specific, mandatory list of items that shall always be read back. While "ATC route clearances," "runway-in-use," and "altimeter settings" are on this mandatory list, "surface wind" is NOT included as a mandatory readback item. Surface wind is important information (often provided with the landing/take-off clearance), but it is not classified as an item that shall always be read back under ICAO's specific list for critical control instructions. The inclusion of an incorrect item (surface wind) makes the entire statement about the "always read back" list inaccurate.