Thanks for good words about the plugin!
Also thanks for ready to donate! hmm, I can do custom skin for you based on LenSlider =) sovletig(DOGGY)yandex(DOT)ru
About Vania Fit rotate (information for free=):
Yes, you can, just go to
/wp-content/plugins/len-slider/skins/vania_fit/output/js/custom.js and update line to
the example contains 6000 (autorotate with 6 seconds interval) - you can change it as you wish.
BUT: now i take a time to make a new version of the plugin with autorotate option and much others changes. I think autorotate option not will be in next version and if new version will be and you'll update the plugin - WP delete plugin files and then copy new files, so this changes will be deleted and you will need to do it one more time..