How much time we can spend in this museum?

I would say 1.5 hours, but depends on you

About 2 hours depending on your depth of reading and interest in the art on display

as much as you like, but realistically, you'll spend approximately 2 hours there (maybe less)

As much as you want...

2-4 hours would be the perfect visit, depending on how many exibits you want to see. But you can stay until closing if you feel like it.