BSDs handle WiFi fine as long as it's a supported device. Generally meaning there's a BSD-compatible licensed open-source driver for it.

Battery life hasn't been the best story but at present it's pretty good. Same with Linux on that front, maybe still lagging a bit.

If you're going to be running a BSD on a laptop, do some research first and buy one that's well supported. Thinkpads are generally a good choice AFAIK, but you need to look more deeply than a brand or manufacturer.