Form in the formless realms

Dependant Origination declares that from Consciousness (Viññana) arises Nāma-Rūpa, not just Nāma. Therefore it is implied that even in formless realms the entities that exist there also have a form of some kind. Uddakka Ramaputta and Alara Kalama were most probably born in formless Brahma realms after their death. But Buddha didn't visit Alara-Kalama and Uddakka-Ramaputta which means that they couldn't understand the Dhamma which must have been a problem with the senses or something similar (My first question) because they already had superior mental ability to understand the Dhamma (MN 21 ), > Alara Kalama is wise, competent, intelligent. He has long had little > dust in his eyes. What if I were to teach him the Dhamma first? He > will quickly understand this Dhamma. Dust here implies the 5 hindrances . > This Uddaka Ramaputta is wise, competent, intelligent. He has long had > little dust in his eyes. What if I were to teach him the Dhamma first? > He will quickly understand this Dhamma. I would like to get an answer to either or both (if possible) of the below questions, **Question 1**: Why couldn't Buddha teach the Dhamma to Uddakka Ramaputta and Alara Kalama. **Question 2**: What is the difference in form between the Rūpa Lōka and Arūpa Loka.