(a) trim ... new mouldings is about all you can do unfortunately. Only cost feasible if you source from someone already making the correct panel due to costs associated with developing moulds etc.
(b) seat trim and carpets. Apart from the certification for completion of maintenance issues, the main concern is to look at burn characteristics. Having done many, many burn tests over the years, I would avoid just about any run of the mill commercial fabric and typical FAR 23 qualifying materials like the plague and stick with self extinguishing FAR 25 style materials.
For foams, use a good fire retardent product.
For fabrics, the PFZ process done during weaving is excellent. There are several post weave fire-retardent processes which work varyingly well but you need to be careful of deterioration during washing/dry cleaning. Some processes perform better than others from this viewpoint .. and some are dreadful.
If you are local/near Oz, send me an email and I can suggest some contacts.