SLOB design/parameter questions?

So my drivers arrived (8 Dayton 12” DVC subs) and I’d like to start making saw dust next weekend but I just want to finalize some questions to make sure I’m on the right path here

The depth of the slot?……..so the distance from the front of the slot to the rear…..that’s a 1/4 wave acoustic low pass function, yes? A 13” slot will produce a high cut starting at 250hz give or take? Is there a rough idea of the slope?…….is/can the slope be acoustically changed with some other physical criteria?……the volume of the slot?….the shape/dimensions of the slot?……the shape of the outlet?

Have I read/understood this correctly…..the area of the slot exit should be roughly 1/3 the SD of the driver? If so, what is the basis for this?……what performance criteria is determined…..do the TS parameters of the driver play a role here in optimizing the slot area?

Would lining the slot with absorbing material such as felt serve a purpose?

Thanks for reading!