I have had good luck with Brakefree CLP. It is advertised as a Cleaner, Lubricant and Protectant... However I do not use it as a cleaner, there are cheaper better alternative for that.
Wilson mags are good quality, but I am wondering if the feed lips have spread overtime, this would explain the loaded rounds jumping out of the ejection port though, it really sounds like the cartridges are getting free of the magazine before they are reaching the chamber...
Back to your slide/frame fit... If you disassemble the pistol and just place the slide back on the frame and move it back and forth it should run smoothly with no gritty feeling. If it feels rough and gritty I am guessing you have a "galling" issue. Good picture of the frame rails would quickly indicate the issue too.
If galling is present it is due for a trip to a gunsmith, or if you are semi handy you could probably deal with it yourself. A light sanding with 600 grit wet or dry and some solvent for lubricant on the frame rails and the corresponding mating surfaces inside the slide should get it running smoothly again.