Do we need to bring an idol of the Vastu devta for the Vastu pooja?
No. Keep the samagri simple and do the pooja from the heart; any pooja is an offering of feelings, and what matters is the bhav offered, not whether paan or gud could be offered.
Related questions
Are there 45 vastu devtas or 49?
There are 45 devtas, but 4 more devtas stand on all four sides to protect them, so basically there are 49. Bhog samagri is offered to these 4 guardians as well, after the 45.
Can a Khajuraho statue be kept?
If it is kept with a purpose there is no problem; it depends on the purpose for which the statue was made and is kept.
Can a Laughing Buddha be kept at home?
No. Einstein is said to have wished at the end of his life to be born in India to research its sacred soil, the land of the Tirthankaras, Ram, Mahavir and Hanuman. Indians need not keep meat-eating foreign deities such as the Laughing Buddha or the Chinese Fuk Luk Sau; keep portraits or statues of Ram, Hanuman or Mahavir instead, and do not let them be dwarfed by such figures.
Can a black statue of Buddha be kept?
A statue of Lord Buddha can be kept, but not a Laughing Buddha.
Can a photo of God be put up in the Brahmasthan?
Yes, there is no problem in putting God's photo in the Brahmasthan, because it is the place of Brahma.
Do paintings or decorative idols of God also need correct placement?
Yes, they also represent a planet and should be placed correctly. A consecrated God's photo should face North or East, or West if that is not possible, but never South; South-facing is for the photos of ancestors who have left this world.