Bathroom GFI Receptacle and Light Wiring

[chuck b]

Wiring a new cottage (Michigan) bathroom. The local code requires that a 20-amp receptacle be installed that is GFCI protected and that no other receptacles are on this line. Can I use a 15-amp GFCI with 12 gauge wire on a 20-amp circuit, or do I have to use a 20-amp GFCI? I understand that the outlet is only rated at 15 amps that way, and guess that is sufficient for a bathroom. Is that compatable with a 12 gauge wire?

This does not make sense, i.e. that no other receptacles be on that bathroom 20-amp GFCI circuit. Wondering if it means no lighting is to be connected? I would like to connect another receptacle on the other side of the vanity top. Would that require a separate 20-amp GFCI circuit?

And regarding lighting wiring, there will be a heat lamp, vanity lamps, an exhaust fan, AND a light over the shower tub combination in the ceiling. I will of course use a "wet location" trim for the recessed lighting can. Did not see a requirement to GFCI protect lighting circuits. Is this the norm? I do feel however that the can for the ceiling lights above the tub/shower should be GFCI protected in case one touches them while bathing, or would that create nuisance trips? What is usually done there, and for the the other light/fan items - GFCI there as well on a circuit separate from the receptacle?
Will use 20-amp for the receptacle and 15-amp for the lights and fan - is this the norm there as well. Thanks.

[jwelectric]

If the circuit hits only that bathroom then everything can be on that one 20 amp circuit.

If you decide to wire the lights on a different circuit both receptacles can go on that one circuit as long as both are protected.

The can light over the shower will say in the installations if it is required to be protected by GFCI.

If it does and you decide to install a separate circuit for the fan light then it is acceptable to include the shower can on the receptacle circuit as long as the circuit does not leave that bathroom.