I can't test the plugin installation in Vstudio Debug because the new installation process restart the appPool: i don't know how solve this to debug plugin installation.
By the way, i solved all compile problems; during installation i received this error: System.NullReferenceException: Object reference not set to an instance of an object. at Nop.Plugin.Misc.MystonesEasyFatt.MystonesEasyFattPlugin.Install() at Nop.Services.Plugins.PluginService.InstallPlugins() in C:\Users\max\Documents\Visual Studio 2017\Progetti\nopCommerce_4.20_Source\Libraries\Nop.Services\Plugins\PluginService.cs:line 419