1. I was told recently that there is an opinion that one must do mayim achronim only if there are three men for a zimun. I’d never heard of this. Is this true?
2. Would it be permissible for a woman to do netilat yadayim, refill the natla for her husband, and then to bless and dry her hands? Or first she should complete her netilat yadayim and then fill the natla?
3. There are three roommates, two of which are sephardiot and one is ashkenazia. They bought china together. Would they need to tovel it for the ashkenazi?
4. If a woman, who is particular to pray shacharit everyday, and not mincha, gets caught up and finds herself before chatzot with enough time either to say shema or to daven shemone esrei, should she say shemone esrei and after chatzot say shema? What if she is not particular, and sometimes prays mincha instead of shacharit?
1 No, this is an obligation even on your own.
2 There should be no interruption between her washing and the blessing.
3 Toveling China is not a Sefardi/Ashkenazi issue per say. Many are stringent to be tovel and if any of the three follow this opinion it should be done [without a bracha].
4 She should say Shmone Esrei rather than Shema, as Tefilla is an obligation for women, while Shema they are exempt from as it is a time bound mitzvah.