「祝你找到一个好工作」 means "Wish you find a good job".
It's usually used when somebody is hunting for a (new) job,
「恭喜获得这个工作」and「你的新工作表示祝贺」 are quite natural expression.
But from my point of view:
「恭喜获得这个工作」 --> 「恭喜您获得这个工作」
「你的新工作表示祝贺」 --> 「对你的新工作表示祝贺」
are a little better.
You can also say 「祝您今后在工作岗位上大展鸿图！」 to wish other people a bright future on their new job.
This is an incredibly broad question; books can be written on the subject. Because of this and I'm not an expert Chinese language user either, I'll only answer using broad generalisations (and exceptions will apply to everything I write here).
These are the words and phrases commonly used during Chinese New Year:
General well-wishes: as an ...
The simple and direct translation of
Congratulations on your new job!
This is mostly used when you know that person but not very close to him.
If you know him well, then you should say more, such as suggested by fabregaszy 祝您今后在工作岗位上大展鸿图 !
Everybody likes to hear good words!
恭喜 is more colloquial.
祝贺 is more literary.
Both can be used as a verb for "congratulate"
"Everyone goes [congratulating] Mr. Li who has added a son to his home."
Since 恭喜 is more colloquial, it is the one we use as an exclamation in speech:
"恭喜恭喜! 恭喜你們家中添了個小男孩"(Congratulations!! Congratulations ...