Adding 你, 你們, 您 after interjections

Question

So I've noticed that for 謝謝 and 歡迎, it is common to put 你 or another 2nd person pronoun afterwards, though it's not required.

謝謝 vs 謝謝妳
歡迎到佛蒙特 vs 歡迎你們到佛蒙特

I'm assuming that because these expressions are interjections, they are fossilized to an extent.

My two questions are;

1. Is there any difference between adding or not adding 你? Like how in English 'thank you' is slightly more polite than 'thanks'. (I realize that adding 你們 instead of 你 would change the meaning, I just mean adding the second person pronoun in general.)
   
2. Are there other verbs/interjections that behave this way in Chinese?

Answer 1

1. 你, 你們, 大家, and XXX (a person's name) are often inserted to intensify the welcomeness towards the person/group in focus.

2. I'll come back if I find one.