1) How can I change the Slider Transition timing?
You can achieve this by heading into Admin -> WeltPixel -> Sliders Manager, and selecting the desired slider. Click Edit and scroll down to the Autoplay function. Under it, you'll have an Autoplay Timeout box. That's in milliseconds, and you can change that to whatever you wish. For example, a value of 10000 will make it so the slider changes in 10 seconds.
For carousels, head into Admin -> WeltPixel -> OWL Carousel Settings -> AutoplayTimeout, and set the desired values in milliseconds.
2) Great, but how to I change the order in which the banners are displayed?
This can also be achieved via admin settings. Head into Admin -> WeltPixel -> Sliders Manager, and select the desired slider. Hit Edit and then, from the menu on the left hand side, select Slider Banners. You'll then have a table with the available banners, from which you can set the Sort Order.