Guess me ; Seven letters are we, Four different words we make. Guess us or be ridiculed; Your reputation's at ..........

Question

Seven letters are we,
Four different words we make.
Guess us or be ridiculed;
Your reputation's at stake.

The first has pictures,
Paintings and such.
The second causes sneezing,
From ragweed or dust.
The third is an adverb,
It's hard to explain
It's the same as immensely
But it's much more plain.
If you can act like a king,
this word you will sing.

These clues are sparse
This riddle may be tough.
But if you are smart
Then it will be enough.

Answer 1

Gallery, Allergy, Largely and Regally
A gallery has pictures and paintings
Allergies make you sneeze
Largely is somewhat difficult to describe - it is certainly a synonym for immensely, but not as strong.
Regally means to act royally, or kingly.