I'm new to this domaining world and want to invest in domains.

I have a few questions rather confusions whether the domain value remains same, increases or decreases if i follow the below things.

1. when buying a .in domain is it necessary to target indian market or we can target the world market. [Ex: can the .in domain contain the word america]

2. How to self appraise a domain name before purchasing.

3. If the .com/.net/.info of the domain is not available but .org is available then what value can it fetch. [.net went for around 5k$]

4. when to sell a domain

5. Should I park the domain or create a small website.

6. how to check whether the name is trademarked or not