Of course, synonyms will all have somewhat different meanings or ranges of meaning; otherwise we would be able to get by using just one word for all of them, wouldn't we? On the plus side, it looks like all the words you've listed are the same part of speech (they're all verbs), so grammatically, their uses are the same.

Not entirely. Synonyms will often have different prepositions or be used in different contexts. You can't often simply replace one word with another.

Many times synonyms are interchangeable, but not always. It really depends on the contact. All of these are correct: Will you be joining the conference? Will you be participating in the conference? Will you be attending the conference? Will you take part in the conference?