Regarding the intercept of the VNAF fighters I think PLAAF's electronic attack capability helped out a great deal. The USN supposedly crippled the communications network of the entire Nanjing military district during the 1996 Taiwan strait crisis with just a single Prowler. On the other hand it is my personal belief that the J-10s would've done well had China not employed electronic attack due to the superiority of the J-10As, when compared with the Su-30 MKKs, in air to air combat. There was an official leak, back in late 2010, concerning the "shoot-down" of 5 out of 6 Su-30s by J-10s during an exercise. The only Su-30 that escaped was piloted by one of the premier Su-30 pilots in PLAAF (surname Yang).
With good Jammer support I suspect even a J-8 or a JH-7 would have no trouble lock on a Su-30... they would just see their radar scope go snow white and RWR going off.
Hey wouldn't some JH-7A got converted to Jammers? any ways. no need for dog fights.