بسم الله الرحمن الرحيم
It is your kindness and good conduct with your Sali. May Allah enable you for more support!
When the amount of zakah and sadaqah reached to your Sali she became its owner. Now food offered by her shall not be of zakah for you, rather it turned food of pure money. Hence you may eat at her home along with your family, there is no harm. Whenever you have a chance to eat at her home, you should give her one or two hundred rupees as gift.
(2) If you are not already sahib nisab, zakah shall be wajib after completion of one year; otherwise the year of stock-in-trade will complete when the year of gold and silver will complete.
(3) If the amount of rent, after spending the whole year alone or by including other zakah-able property, reaches up to nisab (nearly 27000) then zakah is wajib, otherwise not.
Allah knows Best!
Darul Uloom Deoband