If you can "tolerate" Mobil1 (we believe the Toyota oil is manufactured by the same plant), Walmart sells the large 5-Quart 0W20's for around $25. Best price I've found for 0W20...
I buy OEM oil cartridges from Amazon. I purchase other oil (like "Transfer Case LF") and other OEM Parts online from Toyota Part Sales of Dallas. Good prices - and you might be able to get your local Toyota parts dept to price-match if that interests you.
Not sure on #1 or #3, but I will say my calipers are still looking as good as new after 66K Miles and my first brake job a few weeks ago...
Also curious on the BS of the TRD wheels vs a stock SR5 wheel - I'm sure the info exists - I just didn't bother searching for it myself. Also, just FYI: Someone makes a generic TRD Kock-off wheel that is 17x8 with 5.5" BS. They were listed on eBay but seem to be gone now.