Here, troppo is being used as an adverb meaning too, so it does not change.
When troppo is an adverb, it stays the same.
But it can also be an adjective, and then it does agree:
So in Questa birra è troppo fredda, troppo is invariable because it modifies fredda, not birra directly.
Yes, but Questa birra è troppo fredda is the most neutral and natural order.
You may also hear variations for emphasis, such as:
That can sound more expressive, like This beer is too cold with extra focus on the comment.
For learners, the standard order is the safest choice.
A simple approximate pronunciation is:
KWES-ta BEER-ra eh TROP-po FREHD-da
A few helpful points:
Those doubled consonants are pronounced more strongly than in English.