Am I required to perform Tawaf al-Qudum for Hajj if I remain in Mecca after Umrat Ramadan, and how do I intend Hajj?

You are not required to perform the arrival Tawaf (definition) (circumambulation) if you have not left Mecca after performing Umrah (definition). This is evidenced by the Companions' donning of ihram (definition) for Hajj on the Day of Tarwiyah with the Prophet, peace and blessings be upon him, without passing by the Kaaba for the arrival Tawaf.

One who stays in Mecca after performing Umrah in Ramadan (definition) to perform Hajj, and then enters into ihram for Hajj on the Day of Tarwiyah, is considered a mufrid (one performing Hajj al-Ifrad (definition)) and is not required to offer a sacrifice (dam at-tamattu'). This is because the months of Hajj begin from sunset on the last day of Ramadan.

However, one who performs Umrah during the months of Hajj and then performs Hajj in the same year is considered a mutamatti' (one performing Hajj at-Tamattu') and is required to offer a sacrifice.

Ifrad is entering into ihram for Hajj alone. Tamattu' is performing Umrah and Hajj during the months of Hajj in the same year. Qiran (definition) is entering into ihram for both of them together.