I think it is better for you to hire a bus, hostel with a guide from a travel agent. Anyway, it is necessary to have a night in Huanglong. A few hours there is enough. If you want to stay one night there, you should go back to Chuanzhu Si Temple of the county seat of Songpan County. Emei Jinding Hotel (3 star) should be the only place to choose in Jinding. In Leshan City center, there are many hostels and hotels. Most visitors do not usually choose to stay here, but back to Chengdu, so Leshan hotels are not expensive.