most implementations of wireless are slower than wired connections. A wired connection is typically configured at 100mb/s. Wireless connections come in two main flavors B & G. B operates at 11mb/s. G operates at 58mb/s. There are some routers that tout a wireless connection speed of 108 mb/s. I cannot remember how this type of connection works, however i have heard horror stories of their implementations.
your broadband connection prolly runs around 3mb-4mb per second downstream. So none of these are going to choke your inet access. However, if you want to move large files, such as movies, across your network, you'll want that 100 mb/s speed.
a router is an always on device, so as long as you dont unplug it there will be no boot time.