Like Texarkana pointed out – breeding for a dressage TB, and shopping for a dressage prospect TB are two different things. I won’t even bother to respond to the first post of this thread.
What is your competition goal? This will shape what kind of TB to look for.
In general, the TB of today is a lot better suited (IMHO) towards dressage than it was 20 years ago. Several very popular, high quality stallions of recent years have saturated the gene pool with their quality.
You want to look for a specific type versus bloodline, as Texarkana pointed out – although certain stallions truly stamp in terms of their offspring and if you spend enough time looking at these TBs, you’ll start to pick out who is sired by who in a crowd.
I am seeing consistently good dressage *types from El Prado and his son Kitten’s Joy, Giant’s Causeway and sons (Freud, Stonesider, etc), Congrats or Flatter, Stormy Atlantic, Shanghai Bobby (Harlan’s Holiday), Repent, Wicked Strong, Seville, Berstein, Say Florida Sandy, Go For Gin, Dixie Union.
The above list is by no means exhaustive. Several of these sires (El Prado, Harlans Holiday, Repent, GC, Flatter, SA) have mares approved for breeding in WB books…
Regarding their history and starts… this can be very nuanced and my experience after two decades of doing this is that there is no hard and fast single answer. There are horses with 70 starts that retire in better condition and shape than those with 5. The number of starts is not always meaningful - the connections are much more important. Some horses have brilliant connections and going to a sport horse home is a significant downgrade in terms of therapeutic access and feed; other times, changing hands or career can be good. Finding someone who has connections that you trust can make your shopping experience much easier.
Some things that I tell anyone who takes a horse from the track :
Fix their feet ASAP. These horses get plenty of farriery attention, they are not neglected. Their angles for the track are not in line with sport horse angles. Many come off the track with long toes for the assumed benefit in breakover – fixing the NPA up front and behind is important.
Just about every horse that raced will be backsore. Give them time, good farriery, great forage/roughage, and as much turnout as physically possible.
Most retire with ulcers. Racing is hard work. It doesn’t hurt to start them on a course of Nexium and taper down. It’s cheap and OTC.
Most do not need a break or to be “let down”. They can be put right into work if they are not being retired for physical reasons. In fact, most will acclimate better to their new normal if you keep them in a routine.
Most will come to you knowing the basics: W/T/C, single tie/clip, load, farrier, vet. You may need to teach them to cross tie but they should know how to be tied in their stall. Most will have some exposure to being tack-walked around the property.
Give them as much hay or even alfalfa as possible. They are used to hay in front of them nearly 24/7.
As far as bumps, bruises, knocks, or jewelry… If they raced successfully jewelry is not uncommon. Set osselets are usually fine for lower level careers. Same for bowed tendons and non-suspensory-involving splints. Assess how the horse moves versus how their legs look. Most vets can tell you whether an injury is career limiting. Some jewelry after a successful career is normal; but make sure to look closely at their pelvis. A little variation is normal as all horses have a dominant side, but any obvious asymmetry is a significant finding and may be something career limiting.
If I think of more, I’ll post. 
Hope you have fun on your search.
