I have a 4-cyl G6 like you, though I have the 6-speed. I've found that with all of the GM cars I've ever driven with the console shifter like the G6 you only need to push the button on the shifter in long enough to get the shifter out of the park position, then if you release it you can pull the shifter down all the way until it stops and you'll be in the normal Drive position. From there if you push upward without pushing in the button it'll go into Neutral but no further without pushing the button. Push the button and push up one notch and you're in Reverse. Then from Reverse you can pull down into Drive again by just pushing the button in enough to release it from Reverse. That may not quite replace the visual confirmation but that works as a by-touch indicator.
No idea about your shifting issues as my 6-speed shifts much differently.
2009 Pontiac G6 Sedan - Ecotec 2.4L I4, 6-speed Auto, Sun & Sound, Performance Red, 15k miles.
2002 GMC Envoy SLE - Vortec 4.2L I6, 2WD, 3.42, G80, T/C, Indigo Blue Metallic, 125,000 miles.