The primary drainage objective on a lot is to make sure water drains away from the structure. There won't be any negative consequence to the structure if you lower the height of the berm. If you lower it so much that water spills onto the slope on the other side of the fence, there may be an erosion consequence that you mentioned earlier, but there should be/have been steps taken to establish erosion control plantings on the slope so that erosion is prevented. The ponding sound as if it occurs only during the storm but does not persist after. I wouldn't consider it to be an issue worthy of much attention unless the house was threatened. But it doesn't sound like it is. If that were to change in the future, then you might need to look into increasing the size of the buried pipe Hopefully, someone will advise you on how to control or eliminate Kikuyu grass. I'm not familiar with it. See if you can get, or find out where to get Marathon seed from Saddleback Supply: 800-286-7263. Marathon is a trade named dwarf tall fescue blend. If you can't locate some, you may be satisfied with another competing variety of dwarf tall fescue. You'll need to do a little research to see what's available and if its characteristics will be acceptable to you. If you can obtain seed, you can grow a lawn from it, and with fescue the cool season--now--is the time to do it. As I mentioned before, when the yard is bumpy, it is usually sand that's used to fill in the depressions and smooth it out. But really, anything like dirt will work. Sand is the easiest to use and doesn't decompose ... requiring touching up later. But touching up is a relatively minor issue. Each irrigation valve is one zone. The objective would be to have one zone providing water for plants with like watering requirements. I wouldn't know how much work you need done in order to have that happen, but you should be able to get an irrigation specialist to provide a ball-park estimate and then work through the system accomplishing your objectives. I'd at least explore the reconfigure and adapt option before doing a complete rebuild. You may need to provide some leeway as sometimes pinpointing a price for work like that can be harder than the work itself. If you require an exact price, the bid might be higher in order to cover possible contingencies. If it were my yard, I would create a very simple plan that shows how the yard should be divided into watering zones. It would be nothing more than the plan you've posted here (of the entire yard) with "circles" (outlines) around the various watering zones/plant types. Where an area is too large for one zone (like turf) it would be subdivided, but the irrigation tech can appraise how that would best be done. Discussing your "plan" with them would allow you to see if you and they are on the same page for the work. If you talk to one company and they can't help, try another.

DO NOT TILL, just to follow up and agree with neliaz. If the contractors left your soil surface uneven, then the box blade is the universal solution. If you sod, you can do that any time from now on. If you decide to go with seed, wait until mid June. Bermuda seed needs hot soil (not hot air) to germinate. That would give you many more months to worry about erosion. Until then you can just mow the weeds and practice taking care of it like it was Buckingham Palace. Seeded bermuda and sodded bermuda are two different varieties of plant. They do not mix well in a yard, so think about that before you go buy any seed. Never seed bermuda to patch up a thin spot of hybrid (sod) bermuda.

I was sort of in the same boat last year. I did a small scale experiment in the back yard the same time my builder spread seed and straw on the rest. What I have found is that any topsoil will do. I bought the Lowe's $1 per bag cheap stuff and the Scott's $2 per bag topsoil. I spread the two types of soil in seperate areas of the yard that get the same amount of sun. The Scott's soil did not help the grass grow any faster or thicker. (Remember this was my experience) Both mine and my neighbors yards were put in on the same day and mine is doing a ton better. There were two things that I think really helped my yard develop better than the guy next door. 1) Rake up all straw once your grass starts to grow. When I did this, the grass seemed to fill in a lot more than my neighbors. I had a fraction of the weeds also. I found the best way was to rake it all up into rows and run over it with the mower with the bagger on. 2) Arriate. My neighbor did not do this, but I did last fall. You will not notice very much difference by the time snow hits, but in the spring the results are night and day! If you haven't done this before just beware that clay will cake to the tires of your mower and you will have to clean them off. Not a big deal. Lastly, I bought some of the Scott's Patchmaster this spring to re-plant in an area where we had a drain put in. I didn't think there would be much of a difference, but man that stuff really works. It grows in pretty thick too! If I ever put in another yard, I will definately be using the hydroseeding.

In case anyone cares, I did a hard-rake with a garden rake. It left the rhizomes and stolons of the weeds I killed, but gave me good access to the soil for my new seeds. I sprinkled some compost in a really thin layer over the seeds and everything is coming up nicely.