[matt1234]

Question: Should I spray some kind of weed killer or something on it before I get plants in there?

I would not because the chemicals will get into your food. If you are going to use a weed killer, the best time is the fall--after the harvest. That way, the weed killer will dissipate/dillute over the winter before the next planting.

Instead of spraying, remove the clumps of sod by hand. This will lower the ground level a few inches. But, turning over the remaining soil will fluff it up to make up for the lost height.

[Drill Thrawl]

Leaving the sod gives you some compost.

Another way around the weed issue is to put down about 6 or so layers of newspaper, then mulch. When you plant just poke a hold in the paper where the seed\plant will be.

For a long term option I use carboard and then mulch and let it sit for about a year.