Do we Shias observe the first ten days of dhul hija and have Hadith from the prophet SAW explaining the importance of these days? Such as righteous deeds being more beloved to Allah SWT and sins being forgiven. And do we fast on the day of arafah?

Yes we have hadiths about these 10 blessed days and there are special A’mal for them.

It’s recommended to fast on the Day of Arafah unless it weakens you from worshipping Allah on that day