First of all, I don’t think that the omission of the Latin alphabet is such a big deal; and yes, including it would mean a lot of extra work.
As for additional characters, here are my thoughts:
Currency-symbols: £ is probably useful. I don’t see any need for any others (you already have $, €, and, of course, the Israeli currency symbol ₪). The only reason to include ¥ would be because it is included in the Hebrew code page, which may or may not be a consideration.
Punctuation: You should have em- and en-dashes. A bullet would be good too. Ellipsis is less crucial, but easy enough to do. Copyright and trademark are used in Hebrew. I have never seen dagger or double-dagger (I suspect that they are not used in Hebrew because dagger looks like a cross.)
Quotes: One thing I really like about DavkaWriter’s fonts is that they have left and right quotation marks and, for the double quote, a base quotation mark. Maybe you should think about including them (including a base single quote).
Some thoughts on the Hebrew characters: Some of the Hebrew characters defined by Unicode are kind of useless. The height of uselessness is the final pe with dagesh, which has absolutely no use in Hebrew: a p-sound at the end of a word is always written with a regular pe, not a final. The wide characters seem rather silly to me, and the alef-lamed ligature is kind of outdated.
Finally, a question: Have you abandoned the DavkaWriter-encoded fonts altogether, or are you just keeping them in separate font files? (On my system, I have four sets of Hebrew fonts: standard ones, DavkaWriter fonts, old-encoding Davka fonts, and symbol-encoded fonts which work better with WordPerfect. In fact, the reason I originally got FCP was to be able to adjust Hebrew fonts for use with different programs.)