Regarding oven cleaning you dont say if you have a dipping tank or if you are cleaning all fittings in the clients sink.
if it is the latter Lift degreaser is very good and doesnt leave any white residues as can happen with some of the cleaners that are on the market.
best method soak racks etc in very hot water turning frequently to ensure all surfaces make contact with the cleaning product.
use one of the wire balls obtainable from supermarkets and the grease will walk off the racks badly burned ones may need a bit of elbow grease.
for the oven dilute the cleaning agent in a bucket of hot water ,after warming the oven turn off and dip a clean cloth in the solution and wipe the oven rinsing frequently. For ingrained grease or carbon you may need to use the wire ball. ensure you rinse with clean hot water after cleaning.
care must be taken with Electric ovens do not over wet and ensure the electric is turned off at the socket.
Rubber gloves need to be worn whilst using cleaning products.
Evans vanodine make Lift .