You asked about implantation bleeding. If you know when you ovulate this should be easy for you to figure out. Implantation bleeding does not happen with everyone, in fact, most people never get it. I.B is when the egg digs into the uterine wall to continue growing. Some women experience extremely light spotting, rarely no more noticable than a few spots on toilet paper. It happens 6-10 days after ovulation, thus the previous statement regarding your cycle.
About the second line, unless otherwise specified, hpt's are only valid for 10 minutes after they are used. Because of the cover over the little window, a second line often develops bc of the heat and moisture from the urine, thus called an evaporation line.
Do you have any more questions? I can try to find you an article on it if you would like.