In your two week trial, you are only going t be able to garner how she is as a 'race horse'. Ride her at the walk and trot. Don't do anything that will raise her anxiety, such as chase her loose in a round pen.....this is in most cases foreign to a race horse....being she has only just come off the track, she will be hot. Don't be surprised when you get her home she will sweat, this is an offset from racing. Most racehorses sweat when traveling or when at the races.
Ask the trainer 'does she pull?' meaning is she a horse that travels on the forehand and pulls against the bit.....very common, but not all of them do it. If you find out she pulls, ride her in an enclosed area on a LOOSE rein, any horse of the track will go in to work mode if you bridge and shorten your reins, she will come into and onto your hands. She will be flat, she won't have the foggiest what your leg aids are, as she has spent her life being ridden with little to no leg on.
I THOROUGHLY and STRONGLY recommend you give her some time to let down if and when you purchase her. That means pasture time, wean her off the hot food but watch her weight very closely as she WILL lose condition possibly faster than you can keep it on her. Find a balance with feed for sure. Do bring her in, groom her and act like her behaviour is no big deal if she is hot. Soothe her with a low calm voice....
If she's acting up while you're walking, move forward, keep walking...her behaviour will just get worse the longer you stand still......but do teach her to stand tied up for an extended period.
If its winter where you are, keep her warm, rug her up well, especially if she is pastured.
I have a bank of stuff about this in my brain! But the transition from racehorse to hunter/jumper is best done slowly and positively. Racehorses really respond well to soothing and positivity.
I have been a foreman of two racing barns in Ausralasia and I have also owned an OTTB.
Many people get an OTTB and immediately begin 'retraining' the horse immediately.....they also believe because the horse was a racehorse that he or she has been abused and that would explain the fiery nature or poor ground manners, this is not the case in many many instances. The way racehorses are started, managed and trained is so individual and unique from many other disciplines that when people start working with an OTTB they become overwhelmed with the energy of the animal.....that's why I really recommend spelling the horse, letting her come down quietly and working with her like she is a green broke baby.......small steps equal big rewarding results.
I wish you all the best, please feel free to pick my brain