I'll try to address each of your comments in this post, please let me know if I miss anything.
As far running the scheduler on only specific days, this isn't available in the UI right now but seems like a sensible feature request for a scheduling engine, I'll log it as a future improvement. In the meantime, it may be a little unwieldy, but you could accomplish this by creating a series of 'Every Week' recurring events, one for each day you need to run the scheduler event.
Continuing with the scheduler, since it sounds like your test is from older than the last ~48 hours, can I ask if this behavior has changed at all since we released the new scheduler (late Tuesday, USA time)? If it has not, could you try deleting and re-creating it now that we have the new scheduler engine in place? This shouldn't be explicitly necessary -- we've ported existing events from the old system -- but I'd be curious if it changes things (and if it was necessary in the first place).
As far as trigger creation, I think you're just running into a gotcha in our UI, one we'll be improving soon. Right now on the web it is necessary to drag the parent device for the sensor or actuator you want to trigger into the 'IF' box, which will then produce a dropdown menu where you can select the specific sensor/actuator. You can't drag the sensors or actuators themselves directly.
I don't have an immediate answer for the bit about the increased load time or the boards showing disconnected. I am curious what the type and connection method for these devices are (and number), since we are aware of some slowdown caused by many (non-MQTT connected) Raspberry Pi's and Arduinos on the same account.
Finally, with regard to your last question -- we have been doing some custom work (white labeling, custom dashboards, specific features) for enterprise customers. For more detail on this I would point you to email@example.com who should be better equipped to answer specific questions if you let them know a little about your business case and what you're looking for Cayenne to do for you.
I did want to let you know that in our last update (the same one with the new scheduling engine), we soft-launched a Beta REST API that you can use to make custom web/mobile applications using Cayenne for the core logic and IoT connectivity. It's hidden from the Cayenne UI during this initial soft launch but anyone reading this is welcome to look at it, we'd be very much interested in your thoughts and feedback. (you'll need to be logged in to access it)