Replacing wheel bearings? That's way overboard. If the wheels spin without squeaking or crunching, leave 'em be. I commute ~2000mi/year and haven't touched my wheel bearings since I bought the wheelset 5 years ago.

All the rest of that advice is good though. Don't get sucked into the Chain Lube Holy Wars. Just pick something reasonable and use it as often as it needs to be used (listen to the chain, it is either silent, or it is saying "lube me!").

There's a spectrum between long-lasting lubes, which are dirtier, and cleaner lubes, which need to be applied more frequently. If you've gone 1500-1800 miles and are only mildly perturbed by built-up "cakes of black squack", I'd guess you live towards the end of the spectrum that would tolerate dirt in exchange for duration. The gold standard there is Chain-L.

If you want to be able to use your cassette for a dinner plate, the extreme in that direction is to strip the chain of all oils and periodically soak it in parrafin wax. For this you typically keep a dedicated crock pot of wax. Every few weeks you'd flip the switch on the crock pot to re-melt it, take your chain off the bike and drop it in (on) the wax. When it's melted and soaked for a bit you take it out, turn off the crock pot and put the chain back on. You would need a chain with a quick-link of course, and special quick-link pliers would be worth the investment, and used crock pots are plentiful and cheap at thrift stores. Wax zealots swear it's not much effort, but I prefer to not even think about my chain for 3-4 months at a time.