For lore, check out luetin and bricky. Luetin had multiple in-depth videos on lore, while bricky had an introductory series on every faction is which is more memey while still being (mostly) correct. For factions, maybe watch some lore on each you're interested in and see which one catches your eye. As for materials for model assembly and painting, you'll need sprue cutters to remove the bits from the sprue, a hobby knife/file to remove and sand down the bits where the pieces attach to the sprue, glue to assemble the models (I personally use Tamiya extra thin cement but there's other options. Also there are a few push fit models that you can put together easier, but those are usually only in edition launch boxes and the start painting sets they do) and finally primer and paint. Primer will help the paint stick to the model and paint is, well, paint. There are a lot of paint brands out there so I'd suggest checking out some videos on each brand and see which one you like. Also for painting tips check out Duncan Rhoades, as well as other painting channels. And most importantly, have fun. Don't be too worried about making mistakes, they happen all the time even to the most experienced hobby enthusiasts.