Well, size and steepness of your take off is gonna depend on the terrain and where you want it to send you, but ideally you’ll want it to be about a bike length minimum to avoid it being awkward. You can always experiment as you build, it’s mostly guess work as they are all different.
When you’ve got your take off hit it as hard as you like and see where you land, this should give you some idea where to put the landing. Remember if your building in the dry you’ll probably be jumping much further than in the wet, or vice versa.
If you can, soften/taper off then near edge of the landing so that it’s not a harsh case, it’ll also help the landing last as no matter how small the gap, people will be casing it.