Just got back from the Verizon store and once again, they gave me conflicting information so I went online and chatted with a Verizon sales rep. She gave me the "official scoop" on all my questions. I asked her if there was any place on the Verizon website where the terms of the offer she gave me was spelled out. She said no, but she could put notes in my customer account file so when I go to the Verizon store the store personnel can access my account and see those notes. Basically:
I can get on Edge today using my Maxx HD as a trade in and get the $100 credit. If I want to trade in my Droid 2 Global for the $100 credit and keep my Maxx HD, I have to wait until my contract expiration date, which is Dec.1st.
Here's where it gets interesting.
On Black Friday (and all weekend long) Verizon is selling the 32GB Droid Turbo for $99. If I renew my 2 year contract I can trade in either my D2G or my Maxx HD for the $100 credit. In effect, Verizon is giving me a new Droid Turbo plus throwing in $1.00 to renew my contract. I can do this for all four lines that my family has. I'm strongly considering this. So, yes, you can stack the Black Friday special price of $99 on the Turbo and the $100 trade in credit for an old smartphone BUT ONLY if you renew your contract, you can't do it on Edge.
Besides having the sales rep put these notes in my account file, I printed out the entire chat and will bring that to the store. There is an option to have the entire chat emailed, and I clicked on it, but for some reason I never received it. I also have a screen grab of the relevant info. (Below. Click to enlarge.)