2.Could the "unbreakable" passwords get cracked all the time or can they be found by someone through another way?How?
Typicially with Wireless Local Area Network (WLAN) cracking, the crackers look first to see if you're using WEP, which is ridiculously easy to crack. If you're not using WPA2 instead of WEP, it can still be cracked by collecting the packets involved in the four step handhake process, and then running either a dictionary attack using a long list of passwords, or a brute force attack, which tries to use every possible combination of passwords, given a certain set of parameters.
Since you're using a strong password, these two methods wouldn't prove to viable.
However, there's still a way to crack a WLAN, and that is through a WPS attack. WPS was created to try to make authenticating smart phones easier, since it's a lot harder to type a complex password on smartphone keyboards. It generates an 8 digit pin number, which is entered into the smart phone. The problem is with the way it's implemented. The first four digits are checked first as a group, and then the last three as a group, and the final digit is a checksum value. This reduces the total possible combinations to merely 11,000, making brute forcing it entirely viable.
So even if you use the strongest WPA2 password possible, your WLAN can still be cracked if you use WPS and your router doesn't have a good lockout mechanism, as most don't. WPS cracking can even be faster than the normal brute force if the router has a particular chipset, and is vulnerable to the pixie dust attack.
So the answer to the problem of WPS is simple: Disable it.
As to the question of your connected devices MAC addresses, I don't know. I guess it's possible for a smart phone to have two network interfaces and for both to be connected to your WLAN, but I have no idea. In any case, if you have a very strong WPA2 password, and disable WPS, you should be fine.
The only attacks possible in this case would be denial of service attacks, but there's really nothing you can do about that if you want to keep using wireless ... unless you want to paint the interior side of all your external walls with paint that blocks radio waves and coat your windows with material that does the same ....
So in addition to using WPA2 with a strong password, and disabling WPS, you should also configure your router to only be administered via a wired ethernet connection, and change the default administrator password. If WLANs are poorly secured, attackers can crack into them, log into the router's administrative account wirelessly, and then basically own the lives of everyone connected to that WLAN.