Malaysia customs regulations of 1 litre of alcohol per person but ensure you comply with the 100ml rule, ie no liquid can be carried airside unless it is less than 100ml in volume so ensure you pack it in your bag that will not be onboard with you.
Yes alcohol in checked luggage is permisible.
No, Lufthansa has complimentary drinks and alcohol for all passengers and all classes.
Yes you can.
Yes provided it is "drinking" alcohol and not 200 proof chemical alcohol.
It will depend on where you are flying from. Generally shaving gel is considered as a liquid and it should be in checked-in luggage, not in hand luggage.
If its in your checked luggage, not your carry ons.
All liquids taken onboard in hand luggage, including alcohol, have a 100ml (3.4 oz) restriction. No limits on checked, hold luggage. See related link below.
Yes, checked luggage is X-rayed and may be subject to further screening.
Yes, wine maybe carried in checked luggage.
Yes, you can pack knives in your checked luggage.
Sure, you can put tools in checked luggage, or at least most tools. If an oxyacetylene torch is considered to be a tool, that would not be a good item to put in your checked luggage, since there is some potential for explosion.
Checked luggage is that which has been checked in: weighed, labelled, and taken away to be loaded onto the plane. You don't see it again until you have landed at the other end and the plane is unloaded. Hand luggage is that which you can take onto the plane with you and have access to during the flight.