Can someone explain acouple thing to me about Twitter?

[I love my PRINCESS ♥]

I responded to a celelbrities tweet..
she isn't following me... would she still get it?

and if she responded, where would I see it?

or do they need to be following you aswell?

Even one of my friends who also follows me
commented on one of my tweets
and it only showed up on their page...
is that how its supposed to be?

also... how does it work when people do #thiskindofthing ?

It's soo confusing!