What should a layman do if he finds that Imam al-Albani has given more than one ruling on a hadith (authenticating, deeming weak, or deeming good), and which ruling should he follow? And what does it mean for a hadith to have a متابعة (corroborating narration) or a شاهد (supporting evidence), and does that imply agreement from another narration and authentication of the hadith?

Differences in Sheikh Al-Albani's rulings on hadiths may be due to a change in his ijtihad, so he might authenticate a hadith after deeming it weak, or vice-versa, because new preponderant evidences emerged, or because he ruled on some chains of narration (turuq) of the hadith but not all of them. In this regard, his last rulings are to be followed. As for the meaning of "mutabi'" (corroborating narration) and "shahid" (supporting narration), it does not necessarily imply authenticating the hadith, as it may or may not be strong enough to do so.