Your lawn doesn't look that bad, about average for a fescue-type lawn. If this is a lawn that is regularly walked on, expect this condition. A picture-perfect lawn is one that only gets tread on by the guy who mows it. Frankly, I think that is a waste of space.
Yes. if you do want to re-seed or plant sod pugs, you should de-thatch and lightly cultivate and amend the soil on the bare patches.
The only weed I see is crabgrass. If you want to try to get rid of it, you can use a quinclorac herbicide, but if it is in large patches you may want to manually remove them as you de-thatch, because you will need to re-seed/re-sod there as well.
Let me just mention that a low-maintenance alternative to re-seeding and weeding is to grow an intentionally multi-species lawn. This could just be different species of grass and sedge, but it can also incorporate brightly flowered plants like daisies, clover, veronica, and buttercups. All these plants will thrive with mowing. Of course, the look of it is very different. Instead of a uniform green carpet, you get a tapestry of colors and textures.