That is not an assumption of evolution. Scientific evidence indicates that all life descended from a common ancestor; the LUCA, or last universal common ancestor. Where the LUCA came from cannot be probed by most of the tools of evolution - for example, you can't do phylogenetic analysis on a single unbranched line. I suppose in principle you could do analysis on the LUCA's genes, but except in a few cases (e.g. ribosomal proteins) that may never be practical.
The LUCA could have been transported to earth from another planet, it could have arisen abiogenetically; or it could have been created by a higher being. Deciding between these possibilities doesn't really impact evolution.
That is not an assumption of evolution.
Totally false and you know it. The 'force' of evolution is so called natural selection. That is the mechanistic replacement for God which is central to evolutionary theory. Nowhere does evolution claim that God did anything. It claims that the creation of species was accomplished gradually by natural selection. That the Cambrian creatures were created directly refutes evolution since the claim of evolution is universal. In addition to which as I said, if God created life there is no way that evolutionists can deny that God created man in His own image instead of in the image of an ape as Darwin and evolutionists claim. The Creator cannot be said to be a force that does not exist and could not have accomplished changes in His creation. So yes, evolution is both materialistic and atheistic.