How do I plan dinners that still happen on the bad days?
Plan four, not seven, and make one of them deliberately trivial. The plans that fail are the ones with no slack, because a single late evening cascades into ordering food for the rest of the week.
The rear derailleur skips on the third gear when I push hard.
Cable tension first: a quarter turn on the barrel adjuster while pedalling usually finds it. If it only skips under load and shifts cleanly otherwise, suspect a worn cassette paired with a new chain, which no amount of adjustment fixes.
Any downside worth knowing before I commit?
It commits you to a format that is tedious to migrate away from later. The first weeks also look worse than doing nothing, which is when most people abandon it.