I've been to Istanbul a number of times, back in the day with my now ex-husband, and just pre-covid with three female friends - we're all 60 plus.
Haggling is only if you're buying carpets, goods, etc., you don't have to haggle in restaurants or tourist attractions, so don't worry!
The hotel concierge arranged a private tour guide for us - a lovely young woman who took us on a morning walking tour, think the cost was about 100 Euros which is fine between four. Our airport taxis both ways were arranged by the hotel, so no problem there.
Can't remember the name of the hotel but it was an Ottoman style house, a few minutes walk from the Blue Mosque and Hagia Sophia. I would recommend you choose a hotel in that area. A visit to Topkapi Palace, boat trip out to the many islands for wonderful fish restaurants, so much to do.
Beware of men who invite you to their art gallery, usually after claiming they were once language students in your home town - it's really a ruse to get you to a carpet shop.
If four old gals can have a fun safe trip so can you!