Speaking for myself, I’ve had the same 50 shekel note in my wallet for the past three months - but I don’t get out much.
Israel has gone mostly cashless. Contactless payment, either by card or by phone, is accepted virtually everywhere, unless you’re buying stuff from sidewalk vendors. I’d say you should have a few hundred shekels on you for miscellanea and emergencies; I don’t know what you’d do with dollars, as most places don’t accept them (although money changing/check cashing places are common).
Of course, all this applies to greater Tel Aviv and coastal areas. Jerusalem may be a different story… and possibly a different planet.
Prices are not cheap, although as in most civilized countries, taxes are included. Tips - in restaurants only - are 15%; they can usually be included in the bill.
Some useful apps:
Venmo/Zelle aren’t really known here - the most widely used payment system is a local app called “BIT”. It’s available in iOS and Android. The Apple app is also used, I think.
The most popular food delivery app is Wolt, although the local Grubhub affiliate, 10Bis, is an option…
There’s no ride sharing here, but there is an app called Gett, which basically works the same way except with actual taxis, at taxi prices. Tip for taxis in general (not through the app) - they’ll try to negotiate a price in advance, which will always be too high, but they’re required by law to use their meter. Insist on it.
For busses and trains, get a Rav-Kav card. You can buy them at the counter at train stations or in kiosks. There are weekly/monthly passes, or you can charge them at trian station terminals and many ATMs. Note that bus drivers will not accept cash.