phil- engine oil capacity on these is a tough one to answer because they seem to vary quite a bit. Oil cooler size & placement, filter kits, etc. that have been added through the years make it tough to say especially since you haven't seen it yet. The sump on my 454 oil pan appears 'stock' but doing an oil change, filter and bypass filter mine holds 11 quarts. I've read here that other MH's hold 11, some 8 and others 7. The first oil change that you'll do will probably give you the most accurate answer.
There's probably more but I do remember two other members here, Astrodokk and Swinginping, have talked about 454 oil capacities and you can read the posts by doing a search of their threads, in the members list.
Most RV parts places should have your wiper blades but I'd take an old one with me to match up. Camping World had mine.