Is Tenerife in Spain?

Tenerife IS Spain but technically it's on the African continent.

Of course. Tenerife is one of several islands that make up the autonomous community of the Canary Islands, or 'Las Islas Canarias' in Spanish. It is a Spanish island but it is also ruled by Spain. Just because it isn't mainland Spain doesn't mean that it isn't Spain. Other examples of Canary Islands include Lanzarote, Gran Canaria, Fuerteventura and La Gomera. There are also another set of islands to the east of mainland Spain, called the Balearic Islands, which are situated in the Mediterranean Sea. Majorca, Ibiza and Menorca makeup the Balearics. The Baleric Islands is another example of an autonomous community. Tenerife is as Spanish as Madrid is.

Yes. Churchill did discuss invading during WW2 as did the germans, but they never did. So it has always been Spanish.

Yes, of course it is. See, if you look at the list of the regiones in this category, you'll see: "Canarias". That means the Canary Islands, That indicates that the Canary Islands are part of Spain, right? Isn't Tenerife one of the Canary Islands? Here's another way to prove it: Look up "Tenerife" in the internet...it will tell you it's part of Spain. Of course it's part of the country of Spain. Just as the Shetlands and the Channel Islands are part of the UK, and the Hawaiian Islands are part of the US, and Corsica is part of France, and Sardinia and Sicily are part of Italy, and Corfu and Santorini are part of Greece, etc., etc., etc.