Never heard the word "suffusive" before. I tried to look it up and could not find anything. Only the biggest dictionaries had it. Would "overflowing" not be more natural sounding?
Should be 'effusive'.
"chứa chan" is used as a verb, not an adj. In this case, it should be "một tình yêu chan chứa" to be correct
I think "chứa chan" and "chan chứa" are the same. It is a coordinate compound word coined by two equivalent parts - "chứa" & "chan", which can be put interchangeably in a sentence without changing the meaning.