If you can't find it on Ebay, Rockauto, Quadratec or Morris 4x4, you will probably either be able to find it here or at a junkyard. There's a guy on this forum who can make you a brand new headliner - I have one and they're pretty nice. Everything from the doors forward on the outside of these trucks directly swaps from Cherokees (like turn signal lenses) and some interior parts as well.
Oil wise, 10/30 is a good bet. Some people use Shell Rotella T5 and T6 in their engines with good results. Oil is extremely subjective and you'll find a million arguments for a million products if you look.