engine gunk cleaning

since i have removed many covering parts of my engine (air and fuel intake etc.), i thought i might as well try to clean the gunk off from the surfaces.

1. is that a good idea?

2. what should i use to clean it with? brake cleaner or something else? or just a clean rag?

3. since i have removed the lower intake manifold. the shafts/channels for fuel intake on the cylinder side (through which you can actually see the valves and valve rods) looks very gunky. does it make sense to try to clean those as well with maybe something like a cotton swab or maybe ever tooth brush?