Need drainage scheme - apologies for so many details

Or maybe I don't need a drainage scheme. Guess that is one of the questions I would like to answer.

Kind of complicated but I'm really struggling to figure what I can do now. Don't want to wait until I have the whole back yard planted. Even if I hire someone, I'd like to know what to ask them to do. If anyone wants to jump in at any point below, I'd love to hear any points of view.

Summary: Can drainage holes along the bottom of a city-built 16 ft high brick wall at the back of our property be utilized somehow in a drainage scheme for help in routing water from other parts of our back yard? How should we deal with the sloped trench that is in front of this wall? Should it be just filled with good dirt/organic materials/etc. and not worry if/when we stop up the drainage holes? Drainage holes are below grade and will be covered when we do planting. Planting is not completely decided yet but imminent. We are thinking about planting Azaleas. Bad idea? (is nice shady area.)

More details:

Description:
landscape elements:
1. small back yard (more narrow than wide).
2. 6 ft cedar fence on sides of lot (full length 120 ft from front street curb to back property line
to be replaced by 8ft high cedar fence sometime fairly soon.
3.16 ft high brick wall along back (50 ft wide) built by city to separate homes from freeway (landscaping)
4. along the length of back brick wall (along the bottom) are drainage holes about 4.5 inches diameter, about 4 ft apart, each hole about 6 inches above the ground level
5. on "our" side of the brick wall, starting about 4 ft in front of the wall, there is a slope that turns into a ditch/trench before the ground reaches the wall, the depth of the "ditch" immediately in front of the wall is approx 15 inches. The width of this sloped "trench" is about 4ft. This sloped area exists because there used to be a sewer pipe there that the city dug up before putting in the wall. THIS is the area I'm REALLY in a quandry about.
6. On city/freeway side of brick wall (other side from our property) is intensive landscaping by the city along the freeway. That means there dirt over there as well as a place to drain water (or for them to drain to us.)
7. The slope from the house to the street is almost non existent or in the negative range so I'm wondering if there might be some way to use these drainage holes in the back effectively to help be a destination for water that accumulates in other parts of the yard.

Questions:
1. I was thinking about planting azaleas at the back of our property in front of this wall in a garden where this sloped/trench area would be filled in. The garden would be raised quite a bit (after I figured out how to do the lower layers with rocks/pebbles/drainage pipes). Is this a bad idea? Other ideas?

2. What is the best way to fill in this sloped trench area?

3. Should I try to put weed blocker in front of the drainage holes in the wall so weeds/plants don't clog up the holes? (THIS IS IMPORTANT QUESTION, PROBABLY SHOULD HAVE PUT THIS NEARER TO THE TOP.)

4. Should I utilize the drainage holes some way so I can put a type of french drain with rocks and perforated pvc in this sloped/trench area? filling at the bottom with coarse rocks/pebbles so it can be a kind of rain garden?

5. Should I create some type of drainage area at the back in front of the wall that I could use to route drainage from other parts of the yard to that area?

6. Probably other questions but enough, enough I think. Thanks to those who have gotten this far.

I am far from an expert, but would think you could utilize the existing holes for a drainage system if they aren't blocked on the other side. I'd be very careful about covering them - maybe good sized welded wire screening with large gravel/small rocks for a base, and then I guess you'd have to have something on top of that so your dirt wouldn't just filter down and wash away.

Say ayla, this is out of my league and I must admit I am having difficulty following all that you have described. I know landscape architects are expensive but I'm thinking what you have described would fall within the parameters of an engineer anyway. If you would like to post a bunch of photos I think everyone may be able to better visualize what is going on over there and you might get quite a few more responses.

Thanks to those who tried to get thru on the details I published. I think we have a solution. You know what they say about keeping it simple if possible. Well we're going to leave the trench in front of the wall and not fill it in. This means the drainage holes won't be covered up. It also means that we will have something similar to a French Drain but it will be a totally uncovered French Drain, literally a drainage ditch in our back yard, LOL. It is small enough and the wall is far enough back that I think having a small drainage ditch will not affect esthetics. And it means keeping the drainage holes in the wall from being plugged up will be very very easy.
Thanks again.