Internet is acceptable in the major Canary Islands cities, take in mind that they use it extensively for reservations. A lot of hotel beds are booked by internet each day. On the other hand there are some arbitrary limits in all country related with telephonic monopolies (not exclusive to Canary Islands).

The problem is the massive and often very noisy tourism. Good luck trying to concentrate to make a deadline in Carnaval or in a small apartment in front of the beach. If you choose the zone carefully, neither too isolated nor to close to the hot-turism spots, could work.

Food is cheap, rental vary from very expensive to relatively cheap. Life can be cheap except if you need to exit often from the islands and take a fly, or when need to buy a new car (must be imported and there is only a single guy in the island that can sell you this brand), or need something special.