Yes, customers need to empty the kitchen before the 1st visit. You can also choose it as an additional service while making the booking if you wish the professional does so.

Spraying of a diluted liquid chemical in all/infested areas of the house

No, the customer needs to wait 1-2 hours till the chemical is dry to place back the utensils. The professional will not place back the utensils even if the add-on is bought

The customer should not touch any sprayed surfaces till they are dry. Once chemical dries, do not wash the surface with water and soap, only a dry cloth

The second visit targets eggs which may hatch later, hidden cockroaches and new cockroach-babies. Killing them via a 2nd visit enhances the effect of the service, even if the problem is eliminated after the 1st visit

Application of a semi-solid gel in all/infested areas of the house

Yes, it is safe. However, it is advisable to keep children and pets away from sprayed surfaces till they are dry and keep an eye on them so they do not lick the surfaces later