The back lid will require support material to support the arch, but the rough surface left behind will be on the inside and might help prevent the case from sliding on the collar.
The orientation the parts are already in is the recomended print orientation, due to the large flat surfaces against the bed and minimal support for the lid.
I'd recomend a high infill percentage to improve strength on the tabs of the front cover. Most of it will be perimeters and the time difference is negligible.
PETG or ABS is prefered for durability, but any material should work fine.
There's a small lip to help seat the lid in place. Depending on your printer, this lip may not print or come off easily but it does not affect the functionality.
I'd also reccomend using a M4 tap or carefully threading the screw in, backing it out as you "cut" the threads to remove the plastic. Do not over-tighten it, as it will strip the threads. Some thread locker may come in handy or a small dab of hot glue or silicone can be used if needed.