It's my understanding that in Modern Hebrew, 'abba' [אבא] (which I think comes from Aramaic) is generally used for "father" rather than the older form 'av'[אב]; as in 'ha-abba shel David' for "David's father".
Is 'av' ever used in Modern Hebrew? And if so, in what context?
Similarly for 'ima' vs 'em'.
Also, what are the plural forms (regular and dependent) for 'abba' and 'ima'?