Nice to see you doing plenty of research and asking some great questions.
There plenty of great commited people on this forum willing to help and here to support you every step on your journey with your new boa.
As dave said tap training is definitely a big help, boas have a fantastic feeding response and could probably save a nip or too.
Your new boa will hopefully calm down once settled with regular handling they can become more relaxed and trust that you won't harm them, my hypo img was so hissy and bitey when I first had her but persevering and putting in the time and effort she is a pleasure to handle. She slept by the glass most of the time so I used to slide the door enough not to get tagged and just stroke her for a while, she would be hissing away but I still carried on and eventually she leaned I wasn't going to harm her.
If it's a female you want as dave said they often grow considerably larger than the males, but there are plenty of smaller locak8boas out there, my Nicaraguan Nd corn Island are both under 5ft and 4 yrs old and by female longicauda boa is only about 5.5ft at 3, so all adults, may see a bit bit more growth but not massive, the locality boas are also slimmer than alot of bci(bi) morphs
Good luck and don't forget to post plenty of pics
Sent from my CLT-L09 using Tapatalk