If they really do stretch it, then it means you have to leave them some area to stretch. Eg give them an inch to stretch into two inches. But if you don't know exactly how much to allow, then all your questions about sizing and sharpening are completely moot.
DON'T trust them with this important task. Do it yourself.
Great! So what's the problem?? Just close your logo PSD file, and never open it again.
When you need to use it on a photo, go to File>Place, exactly as my instructions say.
First things first, please make sure you always do your raw processing properly. And I urge you to consider The Raw Class, it will change your life.
To help you with this further, I need to know what screen you have, and which calibrator you have.
Yes, that's looking how I expected. I suggest you move to the actual seat part of the chair next, that's where you'll see the most change. Let me know if you like it.
My personal experience with Acer hasn't been good.
That doesn't look like an IPS screen. You'd be better to look to the Asus "Republic of Gamers" laptops, they're amazing.
So, I was going to suggest a Channel Mixer adjustment layer, with these values:
Red +100, 0, 0, 0
Green +100, 0, 0, -25
Blue +100, 0, 0, -45
Then masked VERY carefully to the whole chair. You'll definitely need this.
Well, just open the coloured one, add a layer mask to its layer, and mask out the existing text, then save that as a PSD.
Then use that PSD as the basis for your new watermark design.