I've read mixed experiences/techniques with porting a Verizon number to Google Voice and I wanted to share my experience.
I had a GV number and my separate VZ number. I was having calls to my GV number forward to my VZ cell phone, but no one really used my GV number. I hadn't given it out. I decided I wanted everyone to call my GV number instead of my VZ number, so that I could have more control over what happens with incoming calls, but I didn't want to update everyone with a new number (my VZ number has been my number for a decade). So, I decided to port my VZ number to GV so that when people called the old VZ number it would actually go to GV first. Then, GV will ring my cell phone (or other phones). This requires you to have a new VZ number since Google basically takes the original number away.
In order for GV to take your number, you have to own it. When I tried to change my number with Verizon (quite easy to do from your profile), it was very simple and IMMEDIATE. I immediately lost my old number, whereas folks said there was a delay, allowing time for you to initiate the GV port from GV. I couldn't start the porting process because I lost the number immediately. So, I had to call and talk to several people to get my old number back. Now things were back to how they were.
Instead, I then talked to a very helpful lady and she led me through this process:
In the end, make sure to speak with someone from VZ. Understand that depending on who you speak with, they might not be so lenient with fees. You might lose any special plans or promotions, but maybe they'll work with you.
Lastly, one lady had suggested to add a second phone (some unused device of yours) to the account, but without a plan. Then port your main number to GV and move that new second phone number to your main cell phone and put that unused device back in your junk drawer. I did not end up going this route, but you might want to investigate this.
I'm sorry, but you did not obtain a proper synopsis with your cursory reading. Thoroughly reading it (if you're actually interested in the process) would have been quite quick and most efficacious. Although it might look long, it's a very concise guide compared to most of the disparate information regarding this subject.
I just chatted with Verizon Wireless online support about basically this same question. I moved and I wanted to get a local number, but keep my old number I've been using for 15 years. They set up a new line with a new number (and waived the activation fee for the new line). I just have to go pick up a SIM card, then the new number will be the number on my device. Then I can port the old number to Google (I'll probably have to put the old SIM card in the device to initiate that since you have to confirm it's your number) and I'll just have the new number. I'll try to update when I'm through.