yes there will be a bottleneck, that cpu is quite slow, not really enough to play many new games smoothly. if you can, an upgrade to an e7500 or something would be a good idea.
You are probaby good to overclock to 3ghz in BIOS with very slight bump in voltage.
I've been running an e5600 @3.6 ghz with minimal increase in voltage for a couple of years now i think and there wasnt even the slightest issue.
2.8-3ghz should even be possible with the stock intel cooler although not recomended.
When you have an issue with the CPU limiting your FPS the lower the resolution the badder it gets usually. You would actually be better off playing at 1920 x 1080. So yes it will slow you down.