You also want to know what the breeder has done to already socialize baby, showers , dogs, vaccuums, bright color toys.... has she been showing baby these things so he not afraid of everything. 5 Months coming from a breeder right??
DNA testing is personal choice the only medical reason to know would be for you to expect eggs eventually and educate yourself on eggbinding, this is when the egg does not come out succesfully and is a serious risk if you are not educated on how to help your bird.
5 month old is just a baby and he/she will adapt to you just fine!! It should be fully weaned( or close) at this point and able to eat lots of goodies.
Welcome to the forum and good luck hope you fall head of heels today ! oh and your repair man was totally wrong if anything Timnehs are more social and less fearfull but this is not proven and most say its about the same. Timneh are indepentent from parents in the wild about 6 months before a CongoAG which they say may play some part.