I replace the release bearing and the release arm. I've never bothered with the spigot bearing, as it's always been ok. Worth getting one just in case.
DMF is there to protect the gearbox, as is the clutch delay valve. The gearbox will rattle if you fit a solid clutch with a sprung plate. Fit a DMF if you aren't interested in performance. If you want performance, fit a lightened solid flywheel with a sprung plate, but the price you pay will be a noisy gearbox, and probably a stiffer clutch. The stiffer clutch may lead to the master cylinder clevis failing.
Just read that you've done the job now, so ignore the above!