1) Is a woman is allowed to have intercourse at the last days of her periods for e. g if the bleeding stops on the 6 day but still she has spotting (not bleeding) spotting like having yellowish or pinkish fluid etc so in that case is she is allowed to have intercourse? The spotting may last for 2-3 days so is she is allowed to have intercourse for all these days or not.

2) Then at the time of taking ghusl does she need to specify all the ghusl like ghusle janabat ghusle haiz or just by making niyat of ghusl is enough?

1) No. It is not allowed, as long she knows that it will not exceed 10 days.

2) She can make the intention of all ghusls in one. However, the intention of one ghusl is also enough for the rest.