Not by plugging it into the ps3. If you have a laptop, you can plug the ps3 into the laptop, and setup internet connection sharing. Be sure to lookup what ports are needed for not only the console itself, but for each game. The ps3 needs 2-3x as many as the ps4, so a bit of a pain, but should only take a couple of minutes to add the port exception into the firewall.

I'm unaware of a ps3 that doesn't have an internal wifi adapter built-in, though. I'm assuming you want the faster speed..

I wouldn't bother unless you have an awesome internet connection.. The one it came with can handle about 50megs per second.. Though if connection quality is an issue, I'd instead look for a wifi repeater. You can plug in directly to most of them, and aren't much more money. Leaves you with more options to reuse later, as well.

I had a repeater used on my ps3, and actually saw a performance increase over the internal wifi, though, only slight.

You best option is always to not use wifi but the cable for gaming - though, this isn't always possible due to router location obviously..