1.
Can anybody explain the difference between Destroy() and DestroyToPool() for timers please?
Mostly I can see Destroy() in oxide plugins but I found this example which makes me confused.

2.
Also could anybody confirm that...

timer.In is just alias for timer.Once

Thanks in advance!

"Pool" is an internal queue in Timer library. When you do "DestroyToPool", it inserts timer into queue so this timer could be used later. It's kind of a potential timesave (just take an existing object instead of instantiating a new one), but I doubt someone even care about this small delay.

Then it's clear now. Thanks.