Dongles and hotspots are similar in function; they just have a few differences.
A dongle is just a tiny piece of hardware you plug into an open USB port on your computer. A hotspot is a tiny square that doesn't need to be plugged into a USB or anything. There are different types of hotspots, but the ones I am referring to are 4G hotspots.Both dongles and hotspots run on a particular cell phone carrier's network such as Verizon or T-mobile, so you don't need to have access to wifi to use them. They essentially become wifi hotspots themselves actually. You just have to pay a one time fee for the device (price varies depending on the model but you can save money buying a used one), then the monthly fee to the cell phone carrier.
Once you turn the dongle/hotpost on, it will show up as a list of network connections on your computer. You then click on it, put in the password and you're connected. You can use them anywhere that you have cell service. To get a new IP, just turn on/off airplane mode (if using a laptop), or just reset the device. Not all cell carriers are equal in terms of pricing, available IPs, and ease of switching IPs. AT&T is probably the worst when it comes to getting a new IP. Often times you'll reset the device and the IP will stay the same. T-mobile can act that way as well, but not as much. And they're overall the cheapest. Verizon has the largest amount of IPs, but is the most expensive. I haven't tried out Sprint or any other carriers. You'll have to figure out which carrier is best for you.
Tethering is also similar. You turn on an option somewhere in your phone's settings, then your phone becomes a hotspot that a computer can connect to. Again, you would be using a cell provider's internet here, so it works wherever you have cell service. You may pay for tethering already in your monthly cell bill so this could be a good start.
If going one of these routes, make sure to keep track of all of your IPs. You don't want to log into two accounts with the same IP accidentally, so just check the IP every time before you log into ebay/paypal and jot it down.
The IP location doesn't matter at all as long as it's in the same country. For example, if you're in the US and you have a stealth account whose address is in New York, you can connect to it with a California IP just fine. IP location tracking can be very inaccurate and can show your location as being a few states away from where you actually are. So you can safely have accounts across the country and use IPs not anywhere near them. The overall quality of the IP matters much more than the location.
