1- There is no reason why a man should not engage in foreplay with his wife when fasting if he is confident that he will not spoil his fast or hers. But if he is not confident of that, then it is not permissible for him to do it. 2- If one spoils his fast with something other than intercourse, such as eating, drinking, masturbating or foreplay that leads to ejaculation, then there is no expiation but he has to make up for this day later.

It is permissible for a fasting person to break his fast if he travels during the day. For more, please see the detailed answer.

If you engaged in masturbation but no semen came out as a result, then the fast is not invalidated. If it did come out, then the fast was invalidated and you have to make up the missed day.

If a Muslim misses fasting for many years, he/she has to ask Allah for forgiveness and repent to Him, and has to fast the days that he/she missed and feed one poor person for each day. If he/she is poor and cannot feed others, then fasting and repentance is sufficient and he/she does not have to feed others.