I will answer my own questions, as I went searching for answers.
Each team is allowed to use the Yield option once during the entire game
A team may be yielded multiple times by other teams
Yields that are present in the race that are not used and do not affect the outcome, may not be aired.
There doesn't have to be a definite number of Yields each season. Season 10, despite saying that there were two yields in entire race, only one aired. Season 12 had no Yields.
So, we will see next week if there are any more Yields.