What kind of authenticate/ authorize / token I need to post something on twitter? And few basics questions

[Mulines]

Hi,

I would like to use

• only rest & java & unirest (lib for requests)

I dont like to

• use: any other libs or other frameworks
• have any web page
• my app to open browser or something
• have gui

Just pure code and nothing else

I have 2 questions:

1. Can sb guide me what kind of authentication / authorizing / token I need to post something on twitter stream? (Like humans doing it but via code)
2. Is creating bearer token (Application-only authentication) the best way to see others people twitter stream? ( I already did this one)
3. Why there are:
   Application-Only Authentication,
   3-Legged OAuth,
   PIN-Based OAuth,
   xAuth,OAuth Echo

and also things like
GET oauth/authenticate
GET oauth/authorize
POST oauth/access_token
POST oauth/request_token
Whats the difference?

Thanks!