Need little help

Octane is another render engine, like Iray. Octane Render Kit is just the bridge between Octane and Daz Studio.

Render settings are kinda beyond the scope of "just do this", I'd suggest checking out a number of tutorials (You Tube, Deviant Art, Daz store, etc) to really understand everything and decide what's best for your scenes and computer. You can also check out any number of render presets that are standalone or included with various products, they can be handy too.

As for gens, "ease of use" would have to be the stock Daz gens, which are included only in Pro bundles (but can be used on any model). Of course they are basic. For more versatility, go with any of the other well known assets. They are only slightly more complicated to use (not really lol, but the difference in quality more than makes up for it. I'd say grab one of each from here, try them all out and see which ones fit your use case best.

There are all the daz pro bundles here. https://zonegfx.com/?s=pro+bundle
They are generally named xxx 8 pro bundle. You need to pick one male and one female for the char family that interest you (genesis 8, genesis 3, etc).
For genesis 8.1, the pro bundles are with the name of the char and are not named 'pro' (for instance Rosa Maria 8.1, victoria 8.1, michael 8.1, etc) and they generally contain male and female anatomical elements. https://zonegfx.com/?s=8.1+bundle
But anatomical element 8 and 8.1 and interchangeable directly.