Does a wireless usb adapter increase the wireless signal?

Wireless adapters make wireless communication possible. The distances depend on the particular model and it's signal strength.

I would use a USB extension cable and hang the transceiver out a window on your neighbors side, close as possible to their wireless router.

like the other answerer's the built in is normally better, the only advantage you could hope to get would be if they had some sort of higher grade router (like MIMO) and you got a card that matched. Otherwise any off the shelf stuff won't be that much of an improvement, the only upside would be if you could get a usb extension cable and have the usb dongle closer to it than your actual system. If they have a standard router, i'm pretty sure a better usb stick won't help you, you would need to look into an antennae, or a card that allowed for a better antennae.

Having said that, if you're willing to front the cash, you could maybe buy your neighbor a better router and agree to be their network tech in exchange for the wifi's

Wireless USB adapters are specifically made for computers without built in Wireless, Wireless built into your PC will be just the same, maybe even better, than a USB adapter.

No. Generally laptops have wire antenna connected from their card and running up into the lid. This give much better signal than a small USB card which has only a tiny antenna built in. Be aware that even with their consent unless you also have the consent of their ISP this would be considered stealing service, as it deprives the ISP of a possible subscription. There are fines in the thousands, and up to 5 years in prison for this. And the neighbor would also be held complicit in this and they can terminate service and again prosecute.

if your using a laptop than your computer is probably already as strong as it can get... i have a laptop and a desktop running wirelessly and the desktop has a usb adapter and its actually slower than the laptop... i would go ahead and try it anyways... if it doesn't work you can always bring it back to the store

NO

=

Generally NOT.

-

Try a directional antenna

- http://www.l-com.com/productcenter.aspx?id=2005

- http://www.radiolabs.com/products/antennas/2.4gig/...