Try to avoid generic ram, you'll be much better off. I've purchased generic ram (not for my laptop) and it died in about a year, and of course generic only has a short warranty period. Look for better ram usually with a lifetime warranty.
They are both used to accomplish the same thing, connect to computers or routers, both can either be used to connect to other computers, or to connect to a router/switch to connect to the internet. One does it with wires, the other without wires. So if you want to connect to the internet you can use either.
If you have a wireless router, all you have to do is turn the wireless card on in the laptop and tell it to connect to the router (give it the WEP key or any other details required) and it should work.
It's not even mine, I have to give it back to the school when I graduate next semester since it's really not worth it to pay about $200 to keep the damn thing. But basically right now it's a big, bulky, expensive HDD Enclosure for my laptop.
Not quite sure what you're asking, but that would be 15 Megabits/sec downstream, 2 Megabits/sec upstream (~1.875 MegaBytes/sec down, 250 KiloBytes/sec up), and as long as you have a 100 Megabit or higher network card, you can handle it. Or if you have an 802.11g or higher wireless card you can handle it.
Since it was helpful for me, I always try to remind people buying online to research their resellers too at resellerratings.com
Don't get stuck with a crappy reseller that makes you pay for return shipping when they screwed up.