[]<ing]

(1) First off, I know that hubcentric is the way to go. But just for clarification, that means that it has the protruding ring on the inside of the bolts, right?

Like this:

Instead of this:

(2) Second, I should be looking for 6x5.5 to 6x5.5 for the bolt pattern on OEM 18s, correct?

 

[Carbeaux]

Yes, the top pic illustrates a hub centric type flange inside the bolts.
Yes, the Titan is a 6x5.5" bolt pattern.