Compatibility with ISP
You should check with your ISP on compatible modems. You should be able to find a list of devices on your ISP's website. If you purchase a modem that is not supported, be sure that you have the ability to set it up yourself. Your ISP may not assist you with setting it up, or they may charge a fee for assistance. Worst case is it may not work at all. If you state your ISP, you may get more relevant answers from the forum.
Yes, you do need a wireless router modem (wifi router modem). The TP Link that you listed is probably a good choice, but I would do some research on product reviews. Also be sure that it is compatible with your ISP. I have a TP Link wireless router that has worked very reliably for about a year. You shouldn't worry about buying a device that's "too much" for your requirements. Buy something within your budget and rely on product reviews from reputable sites such as CNet.