To answer your question(s): no no yes depends.
も can be added onto any particle except for は and が、 which it must replace. Why? Because は implies a contrastive relationship with the sentence or clause that was uttered before (or sentence assumed to be uttered after, or expectation assumed to be in the listener’s head), while が implies identification, both of which are mutually exclusive with the “both” idea of も.
So, アメリカでも is fine, tho it does rest on the assumption that the previous sentence mentioned somewhere else where the jackets are popular, and the more natural way in speech to express it would be to cram both your も groups in the same sentence (e.g.: それは、日本でも、アメリカでも人気がありました。
The first example is a little bit tougher. The も cannot replace the と in your example because ironically in the original english you’ve actually dropped a substantive amount of information (which is an example of english having a surprisingly Japanese language habit). The sentence
"Riders jackets are also called leather jackets" is actually missing an implicit subject/clause, which if included entered would give you one of two grammatical yet unnaturally redundant-sounding sentences:
- “[The things that are called] riders jackets are also called leather jackets.”
- Riders jackets are also called leather jackets (in addition to being called riders jackets).
Now to translate that idea smoothly into japanese, you can (and probably should) use a translation of sentence 1:
「Rider’s jackets」ということは「leather jackets」もと呼ばれていますね。
The only trick with this sentence is it still sounds unnatural in japanese (at least to me), because that sentence construction makes it difficult to discern whether you mean the jackets are called by both names simultaneously (oh, it’s a rider-jacket-leather-jacket), or that the jackets are sometimes referred to as ‘leather jacketsmo’ (since we can’t hear the end quotation in speech, just the と), or perhaps are just called different names at different times by different people, maybe according to dialect.
In order to ensure that you’re only communicating last meaning, the one you I believe you were originally going for, I think you’d probably want to change your 呼ばれます into short form 呼ばれる and use the 時がある construction to work in the も、as in:
「Rider’s jackets」というのは「leather jackets」と呼ばれる時もありますね。
This would literally mean something
"There also times in which ‘riders jackets’ are referred to as ‘leather jackets,’ right?"
which sounds odd in English but makes more sense in Japanese.
That said though, I’m right at the edge of my grammar knowledge here, so if @Leebo or @vargsvans one of the other 60s wanna take a crack at it, maybe they might be able to give you a better sounding option. I haven’t made or seen a sentence like that before, so I’m making an educated guess.
Hope it helps!