"may need a separate PTT as well though, as the adaptor seems to disable the transmit button on the radio."
I managed with the handheld PTT. No separate PTT with the 8.33 Icom adapter. Simple headset-adapter-handheld, with no intercom, as only used in emergency.
My old Icom adapter had a PTT on it.
I get about 15 miles probably, but the 25 Icom got much more.