If one awakes after Alos HaShachar and will be returning to sleep, can they drink or eat then? Or do they need to say Brachos first, because its after Alos Hashachar?
One is not allowed to eat from Alos Hashachar until after davening Shachris. The Chabad custom is in accordance with the Halacha that one may eat if necessary in order to have strength and proper Kavanah during davening. However if one is going back to sleep then one should not eat until they wake up and say Brochos and are getting ready for davening.
Regarding drinking, when going back to sleep one can drink before saying Brochos.
See here with sources:
בנוגע לשתי’, ראה דע״ת פט, ג. ערוה״ש שם כג. ועוד.