Looks like you need to adjust the brakes. That vintage should be self-adjusting, so maybe something else is going on. Cracks in the outer liner don't tell much, but if the flex lines are over 10 years old, I would just replace them. Cracked linings indicate, in general, that the brake shoes have gotten really hot. This can be caused by stopping from high speed quickly (like in drag racing), and will also show evidence of blue spots on the drum faces. Ask me how I know that one.
The other possibility for cracked linings is that the springs are weak. If you are going to replace the linings, might as well replace all the springs while you are at it, and machine the drums. You can pop a boot off a wheel cylinder (check 'em all) to see if fluid is leaking past the cups. If so, fix it right. If you don't have the experience, hire it. Brakes are too important.