Can I have an electric oven in the same plug as a microwave, and if not how hard is it to change a single plug to a double?
Assuming you are in the US, and that when you speak of an electric oven you are referring to one of the electric toaster type ovens that sit on the counter. Is that correct? If so, you can used the same outlet for both, and convert it to a double outlet so you can have both plugged in at the same time. However, both devices draw a good bit of current when in use and if you try to use both at the same time you will most likely trip the breaker on the circuit.
Short answer, you can used the same outlet for both devices, but just not at the same time.