if I solder the jumper pads on the adafruit cc3000 for use with the Arduino Mega will it still work fine with the Uno?
This module is designed to be "plug in and go" without access to anything except the connector pads at the board edge. While there are a number of pads on the face of the board these are for "experts only" access and are unneeded for normal operation.
The only soldering required should be the addition of a 9 pin row of pins to allow the CC3000 module to be plugged into a solderless breadboard or a socket. If this is all you do then the module will work directly and interchangeably with Arduino Uno, Leonardo/Micro & Mega. These are the only Arduino versions that a full library is available for so far. ADAFruit promise more versions will be supported "sometime".
Additional information is available from
WIRELESS / WIFI / ADAFRUIT HUZZAH CC3000 WIFI BREAKOUT WITH ONBOARD ANTENNA
Solder on connector and go ...
Example use weather station
Example use wireless lamp