Not till now. He is still learning about emotion.
Prema means love. The next avatar of Sai would be Prema sai which mean the sai of Love.
Before his introduction in the Manga, Sai loved noone, not counting his odd "Brother-half-love" Sai is not in a current pairing
No.
sai Marys ino he love her because the first time they meet sai said she was the beautifulest girl he has ever meet.
sachin
No one
first Sai, and than Itachi Uchiha (he love her and she love him)
yes off course
Love and humanity
The person who has more love and affection on Sai Baba was said to be Sainath or who get more blessing from Sai baba is said to be Sainath
She already loves Sasuke and Sai
Wait and see