I have a similar awning and gutter on my house. I think I'm going to have to take the ends loose and pull them back and run a water house down one end and wash everything out the other end. It sucks but I don't know what else to do. Now it is running over in the middle, pooling on the ground, and seeping into my crawlspace.
Use a commercial grout cleaning product or a 50/50 mixture of white vinegar and water. Spray the solution and let it sit for a few minutes then scrub with a sponge or brush. Repeat until the stains are removed. It may take multiple tries.
If you put your clothing in there as-is, the clothing and then you, when you wear them, will smell just as bad.
The smell comes from such furniture sitting closed up for long periods of time. I've found that taking out all the drawers, opening all the doors, and exposing all of it to fresh air and, if possible, direct sunlight, will eliminate the smells in ...
You really have two choices:
Scrub with muriatic acid
Do nothing because you don't want to do it right
With either route you will likely need to clean the entire wall because if you only clean the problem area then it will be cleaner than the rest of the wall.
First of all you want to start slow on this with a little spot cleaning to learn what works in your particular situation. I've used power washers with detergents or bleach with success in these situations but you do have to be careful.
Sometimes the cure is worse than the disease. Often when you clean brick or any surface you can end up with uneven ...
OK, you've got two problems: rust and deep mud. I would bet the deep mud is mildew.
First the rust stains. Pour some white vinegar on the rust stains and let it soak in for 10 to 20 minutes. Then scrub with a hard bristled brush, then rinse with cold water.
For the deep mud, mildew, you're going to need a power washer. You can buy or rent one at your home ...