It turns out that if you've already activated the cellular data account on your iPad using the built-in cellullar account management (as I have), then you have to replace the LTE SIM in the iPad in order to associate it with your Verizon Share Everything. The choice they gave me was to get the SIM by mail, (but the built-in SIM would be deactivated) or to take the iPad to a Verizon store and they can do the whole thing there without loss of LTE service. I'm planning on doing the latter.
When the next iPad comes out, hopefully they'll offer a way to put it on your existing VZW account more easily than this.
Ann154 is correct - $10/month for the tablet.
My girlfriend and I just switched over to the Share Everything plan. We each have an iphone and an ipad. I have an ipad with LTE, she has an iPad 2.
We were able to do the account merging for the phones over the phone with Verizon - it was a little unpleasant and had a lot of holding and multiple attempts before it worked.
When it came time to add our ipads, we couldn't seem to do it via the website, so we went to the store. We used one here in Astoria, Queens (NYC) on Steinway. They were knowledgable and fast. After hearing so many horror stories I was really nervous - but they ran through everything very very quickly and easily.
They *only* had to swap the SIM card in my iPad (with LTE) - with hers, they did not. They deactivated our accounts on their computer, swapped my SIM card out for me, sat around for a few minutes while we waited for everything to register - and boom, done. Didn't charge us anything for the SIM. 20 minutes tops.
It's $10 each per month for the ipads, we're actually saving a pretty huge chunk of change, and working with a larger data bucket, so good deal so far.
It's weird now that if I go to the "cellular data" portion of my ipad it says "You cannot manage this plan on this device, call this number instead..."