estamos or somos
When do I use "nosotros estamos" and when do I use" nosotros somos"?
What actually determine the use of either?
I once got this link in a simular question
Espero que le ayudar
Generally, ser is used to define and identify people things for what they are; estar is used for almost everything else, like states, locations, moods, feelings...
On top of that, each verb has some specific uses, like ser to tell the time or make passive sentences, and estar to make progressive constructions (e.g. I am speaking)
ser generally is a permanent situations like how one acts or where one is from.
estar is used in things that commonly change. For example where one is at or how one is feeling.
eg. estamos en casa vs. somos mexicanos
we are at home vs. we are mexican
Nosotros is the we form. The others are (inf. ser yo soy, tu eres, él es, nosotros somos, vosotros sois, ellos son and inf. estar yo estoy, tu estás, él está, nosotros estamos, vosotros estáis, ellos están.) Note that the article is usually not added in spanish except if you want to intentionally highlight the verb eg !él es el ladron!= He's thief! .
The rest is like lazarus said. There are a few verbes where it's not immeiately clear weather you use estar or ser and therefore you'll just have to lern them. Most dictionaris show which one you use.
The temporary / permanent "rule" is one of the least reliable ones: Está muerto. Está calvo, ser joven.... There are studies about how efficient each method is in the long term, and it has been found that this rule should not be given to students of Spanish, as they keep making simple mistakes later on (I studied this when I did my teacher training).