Is it Sunnah if the bride beautifies herself on her wedding in front of the people? Also is it a must that we buy dress for marriage even though we have? May Allah reward you with goodness.
It is not from Sunnah for a bride to beautify herself in front of the guests (but it is allowed if there is no non-mahram men). Yet it is from Sunnah to beautify herself for her husband by taking a shower, fixing her hair, making henna and putting Kuhl, eyeliner.
As for artificial make up:
Sheikh Ibn Uthaymeen said that it is allowed with the condition that it does not harm the skin. If it is harmful (as lipsticks might be) then it is not allowed. Also Shaikh Hassan Al-Banna said that it’s not allowed to put lipstick containing alcohol.
As for the second part of the question, there is nothing saying that you need to buy a dress. You can wear anything from your wardrobe.