makeup fast

Dear scholars, As-Salamu `alaykum. I lived a life away from Islam, so I did not fast for a number of years. Now that I am a practicing Muslim, am I obligated to make up all those days that I missed? Jazakum Allah khayran.

Respected scholars, as-salamu `alaykum. If I have missed several years of fasting in Ramadan, do I have to fast that many to make up for missed days? Or would feeding/paying poor Muslims meals for every missed day be compensation? I skipped fasting Ramadan for 20 or 25 years. Jazakum Allahu khayran.

Respected scholars, as-salamu `alaykum. If I missed fasts in the previous Ramadan and I did not make them up, what should I do? Should I make up for them or fast the recommended fasts in Sha`ban? Jazakum Allahu khayran.