Try our re-instated info resource - "Aladdin's Cave" (Main menu)- sorry it's taken so long to fix
It does say screw but it is a 6mm thread Ted not a self tapper, and yes that oil guide is necessary
I think you also have a stainless one somewhere
Bottom bolt Ted, goes between the crankcase and that frame lug sticking off the frame. It's quite thick TBH, about 10-12 thick IIRC. Max does them in stainless.