There are many aspects of temperature accuracy to consider. For instance, the temperature control system is within +/-0.5C. However this does not allow for temperature spread within the chamber, in order to test this the chamber is mapped using thermocouples, this is referred to as the Temperature Uniformity Survey or TUS. The best ovens are within <+/-5C. Other factors that will affect the accuracy of the oven include air exchange or usable volume.

Oven temperature distribution improves the lower the setpoint value. This is due to the deltaT between room temperature and setpoint value being much closer, reducing thermal loss into the outside environment. It's also because air is "thicker" at lower temperatures and therefore easier to move around.

Where this is a concern for safety reasons or to protect the product inside the oven, you should configure the oven with an Over-Temperature Protection device. These will cut out if a preset temperature is exceeded. Once thing to remember is that the over temp cannot stop an exothermic reaction. If you have a specific concern around fire hazards and over temp then the process needs to be taken into consideration.

Yes, ovens come with a range of controllers that allow a variety or steps, ramps and dwells. You need a programmer to perform this type of function. You can also data log with certain control modules allowing you to recall data after a run.