I'm not sure what goes into a catapult launch modifcation. The SU-27K is the carrier version of the SU-27. It has been modified with arresting hook, reinforced landing gear, etc. Not sure what else would need to be done.
Redesignated the Su-33. See discussion, photos here:
http://www.fas.org/man/dod-101/sys/ac/row/su-30.htm
Notice that the discussion of the Su-30 MKI operated by India shows that a navalized, carrier version of the Su-30 specifically for India has been discussed.
Note that the normal operating radius of this family of aircraft is of the order of 1800 miles.
The wait for a better airplane with similar range and weapons reach, a true successor to the F-14D, had better not be too long. The AA-9 "Amos"/R-33/R-33E/R-37 "AWACS-killer" AAM carried by the Su-27 family and the MiG-31 has a range of 100 miles, almost as long as the AIM-54 Phoenix.
We are again getting into a situation like that the carrier admirals faced in 1942, in which they were outranged and outgunned by the Japanese carrier groups, which had the A6M Zero against our F4F's and F3A Brewster Buffaloes. At least we aren't outnumbered, too.
The F/A-18E/F "Super Hornet" is a worthy successor to the Brewster Buffalo, which helped win the Battle of Midway by tying up the Zero squadrons for oh, ten minutes or so with a brisk target practice and easy kills on their way to the Midway raid.