The collet is the bit that tightens up around the router bit itself to hold it in place in your router. You have different sizes for the different size shafts on bits. The open ended spanner is just that, a spanner, Used to tighten up the nut that pulls the collet tight around the router bit.
The Centering pin fits to the base and is used as a guide to make sure that you are following a centre line on your work.
Router template guide (AKA Bushing) fit onto the base of your router and act as a collar around the router bit.
You set up a template measure the offset between the router bit cutting edge and bushing, adjust your template position accordingly.
As you cut the bushing rides along the edge of the template, guiding the bit as it cuts your material.
Looks like you got the list of things you need down, shame it's going to be another weekend of rain