The lens resolution vs sensor resolution issue is a bit complicated and it seems nowhere near true that in all circumstances the cameras are outresolving the lenses. Here's something from the Canon Rumours site three years ago:
"The highest resolution Canon sensor on the market today, their 18mp APS-C sensors, resolve 116 lp/mm (see quote above for reference and details about how this number is derived.) If we assume a perfect lens, at f/2.8 and 50% contrast, you can resolve about 247 lp/mm, which is slightly more than twice what Canon's highest resolution sensors are capable of resolving (for reference, you would need a 210mp FF or 81mp APS-C sensor to resolve that much detail.) Given that real-world lenses are aberration-limited at wide apertures like f/2.8, lets take a more realistic aperture. The Canon 7D 18mp APS-C sensor is diffraction-limited at f/6.9, so if we assume an f/7.1 aperture, we can resolve roughly around 95-100lp/mm. The sensor is now outresolving the lens at this aperture, and all apertures smaller than f/7.1. At f/8 the lens can only resolve 86 lp/mm, f/11 it drops down to 63 lp/mm, and at f/22 it is at a mediocre 30 lp/mm!! The same lens at f/6.3 would probably resolve just about 118 lp/mm, just ever so slightly better than what the sensor is capable of resolving itself."
So I wouldn't worry too much about that - but it's worth being aware that high f numbers (f/8 upwards) can automatically degrade your images. The diffraction limit varies from camera to camera, Cambridge in Colour website has a calculator that can tell you where your camera is. I regularly get images accepted on SS that are past the diffraction limit (they're more likely to reject for a shot with a shallow DoF than one that is diffraction limited).