IFTTT Supports ewlink & Stringify
Stringify App supports timer/Date time,etc & IFTTT
So I think its possible by Using both IFTTT & Stringify App combination.
This can be done with 3 Applets combination (2 On IFTTT App & 1 On Stringify APP)
Example For your query A) Is it possible to add a timer to a scene?
Applet 1: (In IFTTT App)
If SOnoff PIR senses Motion & switch on a light, Trigger a Stringify Flow
Applet 2: (In Stringify App)
Stringify flow will Start a timer based on Applet 1 request & once the timer is completed it can Initiate another IFTTT applet (Applet 3)
Applet 3: (In IFTTT App)
Once getting the command from stringify IFTTT will trigger to switch off Sonoff ewelink/Sonoff Device (Say light in your case)
Same way for your query B) Is it possible to add a schedule within the trigger can occur? You can add date & time Stringify thing instead of the timer.
Create applet 2 on Stringify first, Then applet 1 & Applet 3 on IFTTT
Above is the idea that I adapted from Internet & it's not my own :)
Try it & let me know how it works :)
I'm trying to make a rudimentary hot tub controller. I'd like to schedule a normal heating scene and a low heat scene to run at different times of day.
Also, the ability to disable/enable a scene so if i wanted to use the hot tub during the low heat cycle i can override it.
Exactly what I want, too. Looking forward for a solution. Ambient light sensor would also be nice, and possibility to combine trigger conditions (AND/OR etc.) in software. Turn light on IF sensor movement AND time is in range OR it's dark... turn light off after 10 minutes from last detection... instead of the ambient light sensor, an astronomical clock would probably be sufficient, too (but sunrise and sunset times differ greatly on different areas, in my country the difference is several hours between the north and south in the winter, so you would need latitude, longitude and time zone to make it work).