Tablets

It doesn't need a wireless carrier to make it work - although some features here and there might work only when you have a wireless carrier.

If you get it without a contract, you can't "activate the 4G". If you want that option in the future, you'll need to get service with an appropriate carrier and the SIM card to connect.

Correct you do not have to buy a Data Contract to make it work though getting Apps and the like and having them work may be an issue. However it all depends on what it is you want to use it for.

Then later on if I wanted to use it I would just have to activate it?

That is what should happen but here it all depends on who you buy it from as it may very well be locked to just the 1 carrier and you have to go to the Telco to have a working 4G network.

Col

Even the Blackberry has the option to disable mobile internet and just use wifi. :)

Most of the companies offer a steeply-discounted price on the hardware when you sign a 2-year or longer contract. Don't be too surprised if they tell you the tablet is more expensive if you don't activate the 4G. The price difference may be drastic.

4G not only kills your battery when turned on and I mean fast but also cost you monthly if you turn it on or not. You pay for 4G and may have very little chance to use and enjoy it unless you travel and the airports or hotels in that location has 4G in the air. Two years ago I paid for a data package includes 4G because the device purchased was 4G capable and where I live and work no 4G to be had and most likely wont for another year or better.