Well basically ohms is resistance, and the higher the ohms ur running on the amp the cooler it will run, but people in competitions run as low as .25 ohms maybe even lower to get the maximum power out of their amps, but this is alot of stress on the amp and the electrical system (and if they dont blow the sub).
The kickers arnt bad, I've heard them before, they pound but dont sound great. I've never owned any just friends have them, I wouldn't go for them since I love sound quality, but since u just want bump its not a bad deal