Ask to see it and see the shot records and vet reports. Every boxer is an individual and their willingness to learn is going to be based more on their early socialization and their individual temperaments than their gender. Many rescue groups will require at least one obedience class for each new family and their boxer and don't be afraid to attend more. It is a great bonding experience and a way to get exercise and have fun. There is no right or wrong answer here.
Microchips are perfectly safe and have been improved on greatly since first introduced.
The horror stories of chips moving does not happen that often anymore and they are very safe when inserted by a professional. The downside is that not all shelters or vets have scanners and not all chips will activate all scanners. The hope is that in the near future, all scanners will indicate the presence of a chip, even if it can't actually read the number. Tattoo is also acceptable and as long as it is done on the torso and not on an appendage that can be removed. Read every book and web page on boxers, their characteristics and temperaments.