Register a subsidiary in USA
1) Can I register the company in US as a subsidiary? If yes how?
2) Do I have to register in all 50 states to do business in all states? For example Our office will be in Florida and if we get project from CA, do we have to register in CA? Sometimes one of our employes have to work in CA to complete that project.
3) What will be the cost? and how long it will take to register?
4) What all documents you need to make this happen?
Technically you have a few options here regarding the initial set-up of your business in Florida:
First option, you could get an equivalent of a certificate of good standing for your Canadian company, certified through the Canadian Embassy. Then you could use these documents to file your business as a foreign entity in Florida. This will be a more expensive and time consuming process.
A much simpler (and more cost-effective) option would be to open a new entity in Florida using your Canadian company as the owner. You would be able to use the same business name for the U.S. entity, providing it is available with the state.
You probably wouldn't need to register your business in all 50 states. You would be able to receive orders from any state through your Florida entity. What creates the nexus is having an office, employees, property rented/owned by the business, or conducting the work in person. In this case, for lengthy relationships it does seem that you might need to file your Florida company as a foreign entity in California.
The costs and process times will vary depending which route you go with registering a business in Florida.