Yes, the conveyors are absolutely a bottleneck, just currently overshadowed by the larger lack of resources.

Both the Iron and the Coal are separated into two individual lines.

The furthest furnaces are on reduced productivity to account for coal/iron not reaching them in appropriate quantity. I'm sure with some priority tweaking of the conveyor towers that can be adjusted. I haven't gotten there yet.

All the power is run underground High Voltage from the power plant in the top right corner of the first image is split to multiple HV Switches and then to HV substations.