Maret

Fermenter higher than the receiving vessel, tube tip kept above the sediment, and go slowly at the end rather than chasing the last half litre. Leave the lees behind. Then top up or minimise the headspace in the new vessel, because oxygen is the thing you are now protecting against.

Completely normal. That layer is lees: dead and dormant yeast, particles from the honey, proteins and solids dropping out as it clears. A thick layer after primary is exactly what you should see.

Rack anyway. Sitting on a thick bed of old yeast for a long time risks off flavours, and racking gives you clearer mead and far less sediment in the bottles. It is one extra sanitised vessel and twenty minutes.