I'm not sure how you can get any easier than the "Easiest beer I have ever made"! In all seriousness, most extract kits are about the same level of difficulty. The only thing that really varies is if there are steeping grains or not. However, I don't think a recipe with steeping grains would be too hard to be your first batch at all. So, in essence: Brew this!
You can certainly use whatever yeast you want to, but changing yeast will change the beer. I have never used saison yeast myself but Saison is a style of beer with a lot of esther (fruity/spicy/funky) flavors going on from the strain of yeast and the high fermentation temperature. So, yes you can brew this with Saison yeast at 90 degrees but the beer will be VERY different than if you brewed it with S-05 or WYeast 1056 and fermented it at 68f.
I would seriously look at making a "swamp cooler" for your fermentation, unless you really want to brew a Belgian Saison style. You can get a big rubbermaid crate, fill it with water, stick the fermentation bucket in it, add some frozen water bottles and keep your temps under 70 degrees i'm sure. No need for a chest freezer yet. You can also look into building a "Son of a fermentation" chamber, but a swamp cooler is the most basic/cheapest you just have to watch it and keep adding ice/frozen water bottles to keep the temp down.
You can even make the swamp cooler a little more efficient by putting a tshift on the bucket/carboy to wick up the water and point a fan at it. The evaporating water will help cool the beer even more. This is probably more effective with a carboy just because the shirt will fit it better but the principle is the same for a bucket too.