voluntary fasts

As-Salamu `alaykum! Is it permissible to break the voluntary fast?

As-Salamu `alaykum! Please, kindly help me clear my mind on the issue of voluntary fasting. Some people told me that I could not observe any voluntary fasting until I have made up for all the days I missed during Ramadan. Is this true? Thanks.

Dear scholars, as-salamu `alaykum. It was reported that when the Prophet (peace and blessings be upon him) arrived in Madinah and found the Jews celebrating `Ashura’ by fasting, he ordered the Muslims to fast as well. How would you explain the fact that he (peace and blessings be upon him) had forbidden Muslims before to copy the People of the Book in many things, yet he allowed this? Jazakum Allah khayran.

Dear scholars, as-salamu `alaykum. Kindly enlighten us on things that should be avoided as well as good acts that are recommended for Muslims during the first ten days of Dhul-Hijjah. Jazakum Allah khayran!

I missed six days of fasting in Ramadan. Is it lawful to fast six days of Shawwal intending both to make up for these missed days and to get the reward of fasting the six days of Shawwal recommended by the Prophet (peace and blessings be upon him)?

On which day should Muslims fast for the occasion of the Prophet’s birthday? If the Prophet’s birthday falls on a Friday, is it lawful to fast that day?

Respected scholars, as-salamu `alaykum.  If someone fasts six days of Shawwal every year, then one year he gets sick or becomes too lazy to fast or something prevents him from fasting, is that a sin? I've heard that if a person fasts these six days one year, he must never give up this practice thereafter. Jazakum Allahu khayran.