Connecting iPad + iPhone to the Internet 101

Question

Sorry for the simple question, but I've received conflicting information from Verizon and AT&T and have seen and hear more conflicting information on the Internet, from various people, etc. Let me start from the beginning...
I currently have an aging MacBook Pro and a cheap netbook running Windows that I take to work with me. I have an account with Verizon that gives me a modem I can plug into either one to connect to the Internet. I'm allowed 5GB a month. I also have an account with TMobile for a cell phone that no longer works. I pay almost exactly $100 a month for the two combined.
I want to upgrade to an iPhone and replace my netbook with an iPad. (I'll probably upgrade my MacBook Pro this fall.)
I need at least 5GB monthly bandwidth allowance for my computers, along with a very simple phone plan. (I use my phone very seldom.)
After making THREE phone calls, I had the understanding that I could get a laptop connection and a phone line for $70 a month using the iPhone's "hotspot" - and that I would also have unlimited usage for my computers. Now I'm told that I have to pay an extra fee to use the hotspot, and I'll only be allowed 2 GB for my computer.
So what's the best/cheapest plan to get 5GB for my computers and a simple phone plan? Can it be done with the cheaper WiFi model iPad and an iPhone hotspot? Can it be done with the WiFi model at all, or do I need to buy the more expensive 3G model?
In fact, what's the difference between the WiFi and 3G models? My understanding is that you can connect the 3G to the Internet anywhere you can connect with a cell phone -  but you don't have to have an iPhone with you. With the WiFi model, you can do the same thing, as long as you have an iPhone with you - and you're apparently limited to 2GB a month. Is that correct?
I've also been told that you can insert an "air card" and/or use something called 4G that will do something or other.
Based on the erroneous information I was given initially, I ordered a WiFi model, and I learned just a few minutes ago that it's ready to pick up at a local store. But I need to figure out all this Internet connection stuff before I purchase it.
Again, I'd like to have at least 5GB a month for my computers and a very simple phone plan. Can that be done with a cheaper iPad WiFi model? If so, can anyone give me a ballpark figure on how much it's going to cost me per month?
Thanks!
P.S. ANY iPad model should be able to connect via free Internet services (e.g. Internet cafes), even if I'm not subscribed to Verizon or AT&T, right?

Answer 1

I'll try to answer a few of your questions:
- the main difference between the 3G+wifi and the wifi-only iPads is the 3G can get data over cell networks and has gps built in. The wifi only iPad has no gps, but still has limited location capabilities via wifi network location database and if tethering via iPhone.
- There is no 4g card for the iPad, but a 3G and/or 4g hotspot device that creates a local wifi will work with the iPads.
- For the uses you outlined, I would get a myfi or hotspot device ith a large data plan and have it supply data/Internet to the computer and iPad. One large data plan should be cheaper than several smaller plans.
- With some of the plans, like ATT's 2gig/30 day plan, if you use the 2gig in 18 days, you get another 2gig/30 day bundle for the plan fee. ($25.00 ?).
You should estimate the use per device and grand total of cell usage expected for all devices and compare plans and costs. You'll know what makes $en$e.
Oh, and make sure you password protect your hotspot so you don't give piggyback rides.
Hope this helps.