What are the main factors that  decide an entity tax filing selection? 

1.) If an entity net income is at 37% individual tax rate, can select C corp without thinking? 

2.) If an entity net income is about 300K, which is a better option? LLC, 1120S, or 1120C?

3.) If an entity with three partners. which is a better option, 1065, 1120S, or 1120C?

4.) if a LLC or a S corp sold after 5 years. can 50% of  capital gain be tax excluded?