Firstly: Visiting Graves on Eid
Singling out Eid to visit graves is a newly invented innovation. This is the conclusion of of Ibn Taymiyyah, Ibn Baz, al-Albani, and Ibn `Uthaymin.
Secondly: Fasting the Days of Eid
It is haram to fast on Eid al-Fitr and Eid al-Adha. Consensus on this was related by al-Tabari, Ibn Hazm, Ibn Qudamah, al-Nawawi, and Ibn Hajar.