Power cable education needed

Oh boy, is this great?!
Ok, I'll start....
First, you have a nicely put together system and a nice room, and the amount of room treatment is impressive.  To your questions, 

• Yes, power cables can make a difference in how your system sounds
• No, that truth is not enough for companies to include more expensive power cables - some don't believe anything more is needed and most don't want to increase their price point by adding something that is often added aftermarket, especially since "audiophiles" mostly have their own individual opinions about cables
• Yes, you should take a look at your power cables to make sure they have adequate gauge for what they are being asked to do, that they are shielded to resist EMI/RFI, and that the plugs stay secure in the sockets....IMO, that gets you most of the way there and might be a good place to stop thinking about it

You will probably get a lot of opinions here but in the end, only you can make the value decision between how much you want to pay and how big a difference/improvement you believe something achieves.  If you search here and other audio forums you will find all the information about power cords you are looking for.  I suggest making sure the cord to your big McIntosh amp is at least 12 awg but otherwise, if your system sounds good to you, I wouldn't worry too much.  If you really want to spend the money, dedicated power lines would be a good start, IMO.

@ronboco - The dedicated subpanel is a great way to power your audio.  The recommendation of trying cables from Cable Co. by @ghosthouse is good too since everyone ultimately ends up deciding for themselves how far down the cable road to travel.