What is the ruling on the bride seeing her new clothes in the hall, and what is the ruling on henna for her?

There is no harm in the bride appearing in her wedding dress in the women's hall or in front of her mahrams (unmarriageable kin) from among men. However, it is forbidden for her to appear in front of non-mahram men due to the generality of Allah's saying: "And not expose their adornment" [An-Nur: 31].