Is the ablution for major ritual impurity (janabah) sufficient to remove both impurities, or is it obligatory to repeat rinsing the mouth and nose and washing the ablutionary organs after the entire body has been washed?

First: A complete ghusl includes washing the private parts, rinsing the mouth, and sniffing water into the nose once at the beginning, because it is a single act of worship and is not repeated.

Second: The intention for ghusl from janabah is sufficient, because minor ritual purity (wudu) is subsumed under major ritual purity (ghusl). An intention to remove the major ritual impurity or to permit prayer is sufficient. Ghusl from janabah is sufficient in place of wudu if it is performed with the intention of removing the major ritual impurity. However, if wudu is nullified by something during the ghusl, the ghusl remains valid, but one must perform wudu afterwards.