My plan, at the moment, is to use it on the ramp as strictly a portable radio . . . with the option of taking it up in whatever I happen to be flying and using it as a back up to the primary comms.
From your earlier posts - not a pilot, yet, but looking for something you can use later. Early use will probably be on the ramp.
Here's the deal with that - that radio, and other brands of handhelds, are all pretty bulletproof and will last you a long time, even with hard use. Don't worry about any of them getting out of date for aircraft use later. Most of them are water resistant, some more than others. Don't dunk it, but if you get caught outside in the rain they'll take it to some extent.
Since you don't plan to use it in-air, don't bother with an external PTT. If you want to do something with it in the future, worry about it later. An external PTT inside an aircraft really isn't necessary unless you don't have an electrical system. In my case, I got the PTT to use it in a glider, but it never ended up making sense for me. Some guys had a small mic over their ear and they'd strap the PTT to the stick or their finger so they could push it with their thumb. Because of the electrical feedback from the short antenna, if you end up with an airplane that has no electrical system, you are better off plugging the radio into an external antenna and then strapping the PTT to the stick or yoke. I've never really worried too much about the external PTT. Worst case in-air, pull out the handheld, plug your headset into the adapter, and key the radio mic.
For ramp use, the ICOM is pretty loud, but not the loudest out there. It's loud enough for ramp work, but you might find you max out the volume. You might think it's loud, but when it's clipped on your belt and you are on a busy, noisy ramp it might not be as loud as you think. If you really want a ramp-friendly system, the speaker mic can work well...as long as you have a place to clip it. In the glider, I'd clip it onto the shoulder harness. I'm pretty sure all the handhelds work in a similar way - you can preset certain freqs and scroll quickly through them, that's nice if you want to program in a Unicom, CTAF, ground, tower, wx, whatever, for the airport you are working.
NAV - you won't ever need it on the ramp. In the air it's not really worth the trouble. More and more VORs are being decommissioned, and it's pretty simple to get a handheld GPS or a tablet with GPS and get way more info plus a moving map. It isn't easy to configure without the manual, and that's not something you want to be messing around with in the air.
Batteries - some people swear by the AA pack vs the rechargeable. If you are on the ramp, you can recharge overnight or whenever. When you start flying, you'll end up stuffing the radio in your flight bag for long periods, then pulling it out to find the battery is low and you don't have enough time to plug in the charger.
Any more questions about it, ask here or PM. I used to be a "power user" but now I only use it for getting the weather during pre-flight.