When you say that you "bought the legitimate version" I guess you mean Pro (basic is free). Pro has a couple of extra features...will connect to 5 ultrapeers compared to basic's 3, so there's the potential for better search results. You can connect to a couple of extra hosts for download, so there's the potential for faster downloads.

Chat's never been too reliable, it's been fixed a bit in later versions but there's still no guarantee that you'll get a response (the host you're trying to chat with might not be at their computer at the time).

Providing that you bought Pro from the official site Lime Wire » Official Website & Free Download, BitTorrent « you would've recieved an email with a link to your Pro personal download page. You can use that link to download Pro as many times as you want while your Pro benefits are current. So if you bought Pro for 6 months, you can download Pro for 6 months & install it on as many computers as you like. Same goes for the 1 year Pro

If you didn't save that link, go to this page & enter the email address that you used to buy Pro...you should get redirected to your Pro download page.
Lime Wire » LimeWire PRO Support Center

There's now a 4.16.4 stable release. There's also a Beta version available (currently 4.17.3), which you can download from your personal download page.