Wa Alaikum Salam.
Although I am not a Civic owner, however, will try to guide you up to the best of my knowledge:
If a catalytic converter lasts 50K Kms / more, then its not a bad thing IMO, considering bad quality of fuel here.
For used JDMs, most of the times, they start getting choked around ~20K Kms, if driven on extremely bad fuel.
Its ground clearance is adequate, provided you pass over the speed breakers reasonably.
If you'll try to cross them at ~30 kmph / more speed, then for sure car will rub against speed breakers.