Switching from Verizon Unlimited Data Plan to Verizon Max?

I'm considering upgrading to an iPhone 6 Plus. I'm currently a Verizon customer with an unlimited data plan (UDP), and I know that there's a promotion going on where UDP customers can get 6GB of data for $30.

My question is whether or not I will be able to switch the data plans online, or if it is something that needs to be done over the phone or in person. If I were to preorder the iPhone online on launch night, would I be able to select the Verizon Max plan on either the Apple pre-order site or the Verizon pre-order site?

Also, I don't really care TOO much about the Unlimited Data; on average, I use about 5-6GB a month, so I'm not taking full advantage of it anyway, and I have no real plans to use more than that in the future.

Who cares

  • Will I get charged for using 3G Internet if I have the unlimited data plan? My carrier is Sprint. I have an iPhone 4. I'm asking if I'll be charged if I don't use Wi-Fi.
  • What's the data limit for Straight Talk's Unlimited plan? I'm probably going to buy the unlocked GSM iPhone 5 and then use it on Straight Talk. However, has Straight Talk said how much data you can use before your data speeds start getting throttled? Also, will the data that I use while I'm on Wi-Fi count against that data limit?
  • What can I do to keep my unlimited data plan on Verizon and upgrade to the iPhone 5? Now I already know that I can buy one full price from Verizon for about $649 but I don't want to go that route, and I don't want to buy a subsidized iPhone 5 and end up losing my unlimited data plan. Would I be able to just wait and buy a used iPhone 5 after it comes out and then have them activate the phone on my account? They wouldn't be able to take away my unlimited data would they?
  • Verizon Unlimited Data Plan- Iphone 4S? I've seen a lot of answers about paying full price for IPhone 5 to keep your unlimited data plan. I have a 4 and I'm eligible for an upgrade now. Does anyone know if I choose to get the 4S (instead of the 5) if I can keep the plan? And would it be full price or upgrade price?