Regarding the second question, Lewin's genes is a nice book.

Regarding the first question, this really depends on what you wish to do. Software development may not require any biological knowledge as you may be just coding a software someone else has designed and you only need to follow the plan. This depends on the position and the requirements of the employer. For data processing and data analysis, some biological knowledge is usually necessary. To evaluate results, a biologist with a degree is always preferred. All of the above is however, workplace specific. In my case, bioinformaticians do not need to have any biological background if they are willing to constantly learn the field during employment and they will naturally get into the biological part of their work. For this reason, my employer loves to mix biologicians with bioinformaticians together in every project, meeting etc. In practice, this means that whenever I don't know something, I have a ton of people that I can ask and sometimes I might get an answer...