Tefilla mincha


Hi is a woman allowed to daven mincha shel chol if she already lit shabbos candles also is it better to daven amida sitting ir wait till later to say standing thank you and Shabbat shalom has


When a women lights shabbos lights she does not automatically accept shabbos on herself. Surely if her intention is to not accept shabbos then she is still in chol mode, and therefore would have no problem in davening mincha she chol.
As to your second question, Amida is to be said meumad (standing-pun intended). It is rarely permitted to be said sitting, although under some extenuating circumstances it is permissible. For example illness etc. Another example would be on an airplane where standing is not permitted and the person had no other time to pray, again a very extreme exception.