I do not have any experience cutting foam. Do you think the layout below would require cutting too close to the edge?

As long as your cutting instrument is fairly sharp, you should be fine

You should be fine. I make a cardboard cutout of the gun, and pin it to the foam using toothpicks, so it doesn't slip. Then, I cut it out using an Olfa knife.
Makes for a much cleaner cut.

I traced everything with white chalk then cut out the shape. Worked great for my DD middy, glock19 and 4 pmags.

you might consider moving the ruger further to the right in the picture. As you bang the case around and roll it around on rough terrain the muzzle is going to work its way to the case wall with that foam at that thickness. even if the ruger is supported by the stock, there will still be enough movement to mess up the foam at the end of the muzzle.

nope, there is a multi page 7 year thread on this subject. I suggest you go look for it. you first shuold make chalk outlines of where you want ot make your cuts. There are many different ways people cut foam, nothing, nothing looks even remotely close to as clean and sharp fitting as using a foam cutting tool, (which many of us own and are happy to lend out to other team members).
I got mine on the EE from another member for about 1/3 the original price ~110$ (msrp) and it is worth its weight in gold. I will eventually sell it to another member for what it cost me.