Capital, but not all that Spain has to offer.
If you only see Madrid, I can say you haven't experienced the beauty of Spain. You MUST take at least the day trips to Toledo, Segovia, or any of the neighbouring areas. As a Muslim, it was a bit difficult to find food as pork is a staple source of protein in these parts (compared to the South where it was miraculously easy). But after asking around to the abundant friendly people, you can definitely find pretty much anything you want or need.
Insider Tip:Check out what the Opera House is performing online, and if you are interested, show up about 3-4 hours before the show starts. If they haven't sold out, you might get to watch for up to 90% off!
You don't need the T-10 metro tickets to get around Madrid. Unless you intend to go further away from the centre, and often. All else is walking distance.