I agree with the Talon grips. I have them on my Shield and they make a big difference.
I'll bite on the slide release question...this is a hotly debated issue! Most people feel that the slide release is really a slide stop lever. Not intended to be actuated to release the slide. They will say that pulling the slide back all the way (after having been locked open) will release the slide stop and then you let go of the slide and allow the springs to do all the work. I happen to agree with them. Others will say that it's perfectly fine to use the slide stop to release the slide and it will get easier with time. I have a FS M&P 40 and the slide stop can be used to cycle the slide fairly easily. I just chose to not do it that way.
You might get a lot of input on this. It's similar to asking "9mm or 40?" Or "how do I lube my pistol", "oil or grease", etc. It's all really good info but you won't get too many folks down the middle on those issues.
Enjoy the 9C, check out the Talon grips.