I don't think that the original card is "more robust," but it probably has less problems in today's predominantly 802.11G environment than more cutting edge (and less tried-and-true) hardware.
Not reconnecting from sleep is a major issue that has no singular fix. It happens not only to Macs, but to PCs as well. Normally, though, selecting the appropriate SSID and clicking "connect" reconnects for just about everybody. Your surmise about multiple networks around you is probably right, but having your router "on a channel alone" may not be sufficient to protect you from the interference from other networks. Being among a large number of other wireless networks means that there is a LOT of RF in the same frequency range all around you, which can easily confuse even the best wireless card.
There are some things you can do to help your situation. First, you can relocate your wireless router within the space you're covering. Sometimes just rotating it (or adjusting the antenna(s)) helps immensely. It's all about signal strength where the client is, so playing with the location and orientation of the wireless router can give you amazing results. Also, it seems that coverage improves when a wireless base is elevated. Moving my access point to about 6 feet off the floor (from desktop level) increased my signal level by almost 50%.
I have seen the "wrong password" thing a few times myself, and fixed it by reentering the password from a saved text file-sometimes it took a couple of tries for this to work.
Wireless networking is often akin to black magic when it comes to more than the most basic issues, so all I can add is try what you can, but only mess with one thing at a time.