RIC is a small AP. I visited once. It was virtually empty in the fall. It located S of Richmond. Ground trans may take 30 minutes to downtown. I expect its easy to navigate. You should have no problems. - Not sure about summer time.
My two cents. Yes, RIC is relatively small. You can certainly get from gate to curb in 10 minutes, so getting off the airport property is pretty easy. RIC is EAST of downtown (not south, not that it matters much), but there is a bit of travel time from the airport to downtown. Should be less than 30 minutes of travel time. More like 15-20, depending on where you're going. Maybe 30 minutes to the West End, if you're headed there. Traffic should not be bad at 10 am.
I would not arrive at the airport much later than 5:15 pm for the departing flight. RIC tends to bunch outbound flights, so security lines
could be slightly longer at that hour. PreCheck will certainly help, but you would not want to take much of a chance given the limited number of flights back to NYC. Also, traffic OUT of downtown could also cause a slight delay, so I would try to wrap up my work no later than 4:30 pm or so, allowing 45 minutes to get to the airport. That's very likely to leave you ample cushion, assuming all goes well, but still allows you about 15 minutes of "wiggle room" in the event of an accident on I-64 or some kind of odd delay at the airport.