It's ok, you must have done it right. If you had imposed a resolution, the dimensions would have been rounder numbers than that.
For many labs it is, yes. But when you're cropping to 11:15 shape, you're doing so because you're NOT printing. Therefore, 300ppi has absolutely no relevance.
Excellent! Then all is well, you have nothing to worry about.
Actually, you do have something to worry about - all your old files are MUCH too big. 7-10MB is outrageous for jpegs. It means you must have forgotten to remove the noise.
http://www.damiensymonds.net/2015/08/about-jpeg-file-size.html
http://www.damiensymonds.net/2010/07/raw-noise-removal.html
Do you mean the sharpening class?