As far as other training tack, my only suggestion beyond a saddle that fits both of you well would be a snaffle bridle with loop reins. If you ride English, that's easy enough. If you ride western, you could use longer than average barrel reins, or invest in a set of mecate reins with slobber straps. Split reins are fine, but its not fun to drop one, and if you're doing "official" training (all interaction is, in effect, training), you don't want to be concerned about handling long reins. Just my preference and experience.
A natural horsemanship style cue stick (Carrot Stick, Handy Stick, whatever. Buy third party and save a bundle), rope halter, and long (15 ft.-ish) lead/lunge rope are helpful whether you're into NH or not.
If you don't already have one, an up-to-date helmet is always a good idea. Even the calmest of horses can be unpredictable.
Good luck with Romeo, I hope he works out for you! Can't wait to see pics!