Are morphemes commonly found at the end of words considered suffixes?

For example: "erate", found at the end of words like accelerate, operate, refrigerate, considerate, nonliterate, etc.

I am a bit unsure as to the full scope of affixes, whether they have to carry a concrete meaning with them, or if they could be common components of words with a more vague semantics.

Also, some affixes, if they are affixes, seem to carry a functional meaning, like "converting" a root from one word class to another, like "sentient" to "sentience". Here, ience/ence is the "converter", but is it considered a suffix, a morpheme, neither or both?

I also recognize that ient/ent is the same as ience/ence, only regarding adjectives.

So, let's get back to the "erate" thing. Common found combination of letters, is it a morpheme, affix, neither or both? Is it just common, or is it functional, like ience/ence, or does it carry a concise meaning, making it simply a suffix? Perhaps it's meaning is just "of or pertaining to a verb/adjective". And that's something I noticed, the pronounciation of "erate" differs whether it is a verb or an adjective.

So yeah, how does it all work?