The fingers and toes themselves aren’t, it’s the fine negative space between them. If you made the same negative space as a small indentation anywhere on the surface of the model, you’d need to increase your mesh resolution to capture that detail, and expect to have to do so.
It won’t if you increase the DM resolution.
As above, if you increase your resolution, the mesh will be accurate enough to form a good reference for retopo.
A human being can make good decisions about how to lay out minimum geometry, for maximum accuracy. At the current level of technology, auto topo solutions can’t replace that. Using zpheres is it’s own separate process that has it’s own pros and cons. A Pro is that because you’re actually building the mesh out of a kind of “bone”, Zbrush can make better decisions about how to generate that “skin”. Dynamesh doesn’t see that, it only sees a volume, and it renders that volume more or less crisply depending on how much resolution you give it to work with.
Zbrush is moving towards a focus on freeform workflows and mesh creation methods that don’t want you to worry about polygons and the underlying geometry, at least not until you need to. You may decide that is or isn’t the right fit for you, but if you decide you want to work that way, you really need to embrace it to get the most out of it. It’s the old ingrained habbits from older workflows that creep in and make us think about something a certain way, but then we discover it isn’t really necessary any more. You may find that when you examine it, your instinct to keep the mesh rez so low is coming from old habbits in the traditional poly by poly modelling workflow, where you’re pulling individual verts, and the more verts that are in there, the harder it is to get smooth curves and transitions.
That’s not really necessary working at medium rez in Zbrush with Dynamesh, but it does require some different techniques. After you’ve pulled out your basic form, or otherwise mashed it together from component shapes with dynamesh, the process wants us to work more like a sculptor, and less like a modeller. Use additive buildup methods like the clay brushes to build form, and smooth down the rough edges. Don’t be afraid to be reckless. Move brushes with wide falloffs and soft intensities can still make broad changes to form, and the mesh is still low enough rez to be very responsive to smoothing.
But whatever. Zbrush has many different tools for free form mesh creation, and Dynamesh is only one of them. If you decide it doesn’t work for you, you have alternatives, or you could always model your base mesh polygon by polygon as many people still do. But to get the most out of Dynamesh, you’ll have to let go of worry about increasing the resolution (my advice is to ignore the existence of polygons altogether, until you need to retop), or adopt the discipline to flesh out rough form first, then start adding finer details like digits.
