The Tavern

If I wear multiple *Corr items, will the chance of corroding myself increase over wearing just one *Corr item?

yes

Not following Xom by any chance, are you?

Does wearing rCorr decrease the chance of getting hit by *Corr?

Does wearing multiple rCorr help more?

I have boots of *Corr/MR/rPois/Regen, gloves of rCorr, and an amulet of rCorr. I have other useful gloves and amulets. What to do?

I believe it does. I would have to see the character to give advice on what to wear.

I have been wearing two *Corr items without rCorr and it hasn't been too bad, but the character is a bit glass-cannony, an Op with +8 slaying and throwing.

rCorr is a binary resistance -- you have it or you don't. "more rCorr" isn't a thing. Each item you have with *Corr has a chance to trigger independent of whether other items with *rCorr have already triggered, meaning that not only does wearing two give you an increased chance to get corroded, it also gives you a chance to get double-corroded.