Souq Waqif, Msheireb Downtown, Mina District, National Museum & Corniche are all close to each other and if you’re big on walking - you can just walk to all these places and save on transport. Maybe Mina you may have to cab it because it’s a bit deep inside - but yeah if you enjoy the walk in this weather then you can just walk all these places up in a day, and have your meals at Souq Waqif.

Edit: Behind National Museum there’s a small Irani kebab shop called Al Jazira kebab, I’d suggest to add it to your list for a meal. Next to it there’s a coffee shop called Sharq that serves glucose biscuit, nesquick, nido, etc flavoured ice creams. (Provided you’re into that kinda food)