I have 2 questions.
1) I was wondering if I can put itr rear lower control arms on my 00 si? I heard that only ctr ones fit because the itr ones are too short?

-- YES, the ITR rear trailing arms will boltup to any 96-00 EK civic. What's too short is the ITR rear lower control arms (LCA), you can't use these on your civic; you'll need to reuse your civic's rear LCA's in order for everything to fit properly.

2)If I get 5 lug then would I get TEINS for type R or would I still get the TEINS for the civic?

-- you'd have to get Teins for an EK/civic, not a DC/integra....all this because of the rear LCA being a different style.

thanks for reading this
kevin