Even if they were derived from the same root in Latin, they came to English by different paths, migrating whatever suffixes they had into root somewhere along the way.
I'd speculate Miniature is probably a root by itself. I'd speculate that minimum, minimal, minimize have common root minim (or maybe minimum with possible dropping of um part to accommodate suffixes -ize and -al). minor and minority same way have common root minor; and minus and minute are roots by themselves.
It depends what kind of reference we're talking about.
Referrals, as suggested by @Autoresponder, is the normal term for "unsolicited" endorsements - for example, A is a satisfied customer who suggests to others that they should consider using B's products/services.
Reference (sometimes referee) is normally used in contexts where B suggest to someone that they should contact A for a "third-party" (in principle, unbiased) opinion on the quality of B's products/services.
There are many other types of recommendation, obviously. Proposing someone as the chairman of a group you're in, or as a suitable romantic attachment for your unmarried sister, for example. The list of words available for all the different contexts is too long for me to even attempt a summary.
I would say the process by which we create words such as recommendee, recommender, and recommendation from [re]commend is linguistic production. The prefix re-, and suffixes -ee, -er, and -ation are usually referred to as productive. Often contrasted to other prefixes/suffixes which were used to form new words in the past, but which are no longer considered acceptable for use in generating new word forms today.
Best Answer
In general, it seems the suffix -ment describes a state, a result if you want, whereas -ation seems to indicate an action.
From the source that @Keep these mind mentioned, we see indeed for excitement:
and for excitation:
Indicating action rather than a state.