Concerning fertility and menopause?

Preface: Excuse my lack of appropriate terms, English is not my native language.

Last night i heard from my mother that my (ex) sister-in-law was having some health issues.
At 35 she started to get menopause.
She is deeply saddened that she can’t get children now anymore (or a smaller chance to get them?).
My mother told me that usually women can get hormone treatment but in her case that isn’t possible because of breastcancer running in the family.
Three questions that came up are:
When menopause kicked in, are you not able to get children immediately, or does it takes time to be fully infertile?
Can an egg be taken away and put in the freezer when menopause just started (is the egg still good)?
If so, can a frozen egg (after it’s fertilized in a lab) be put back in my sister-in-law’s womb or does ahe need a another woman to carry it for her?
Thanks in advance.