I've been jotting down vocabulary I had questions about until I had time to do lookups or ask.

Geode
I didn't find geode in Wells or Lernu, but from other words in Wells, I'm guessing geodeo...?

Admissions
As in, "Admissions rejected my college application". Lernu and Wells both suggest 'enlaso' or 'eniro' for 'admission'. I was wondering if 'enlasejo' or 'enirejo' would work?

Interests
Interests seems somewhat synonymous with hobby, but I feel an 'interest' is separated from a hobby by degree of investment. I was thinking that using -et with the word for hobby would give the full sense I want?

A related question--are 'hobio' and 'ŝatokupo' completely synonymous? Or is there a fine distinction between the two?

Commercials
In the sense of TV--As I typed this I realized to look for 'advertise' and found 'reklamo'. I guess that works.

The "admissions" you speak of is not the admission itself (which would be eniro). It's the office of admissions, which you're referring to as "Admissions" for short.

I'd call it the "oficejo pri eniro", or maybe "eniroficejo" ("oficejo pri enlaso", "enlasoficejo"). A shorter compound form may be misunderstood to be the entrance of an office.

Enirejo already has a more or less fixed meaning; it's a place where you enter, so it's an entrance.

A commercial would be a reklamo, as you've guessed.

Wikipedia has the word "druzo" or "geodo" for a geode. I have no idea where this word "druzo" came from, because the geod/ combination seems very international to me, based on other Wikipedia entries. I'd prefer geodo of the two terms, since druzo has another meaning (the ethnic group living in Israel, Druze in English)

Hobio and ŝatokupo are synonymous. The difference is whether you want to use a neologism (hobio) or a term constructed from native Esperanto roots (ŝat/okup/o).

Intereso is a word that you could use for the interests you speak of. I have found the word used to describe the concept of having an interest in some relatively old texts in the Tekstaro. It is also used for speaking of things like "in the national interest", or "in the interest of good relations", etc. It is NOT used in the financial sense, which is interezo in Esperanto.

erinja:I'd call it the "oficejo pri eniro", or maybe "eniroficejo"

I think I like eniroficejo where I'd like to have a one-shot word and oficejo pri eniro for times when the listener might not be able to break down eniroficejo...

erinja:Hobio and ŝatokupo are synonymous. The difference is whether you want to use a neologism (hobio) or a term constructed from native Esperanto roots (ŝat/okup/o).

Somehow, ŝatokupo seems more satisfying to me in some subjective/aesthetic way...

erinja:Intereso is a word that you could use for the interests you speak of.
...
It is NOT used in the financial sense, which is interezo in Esperanto.

That was one of my stumbling blocks--making sure I wasn't using it in a fiscal sense.

Geodo works for me. There's a town nearby that has a lovely little park in which they have a geode that's large enough can stand inside the geode...very neat to visit.

Thanks for the help, Erinja!

In NPIV there is an entry for Maroto - preferata esplortemo aŭ okupo, kiu ne estas la ĉefa ag-objekto de la homo

I've never come across this word before and I don't know which language it comes from, but the definition seems very close to that of an interest - as in, my interests are Sailing, Riding and Esperanto.

Ŝatokupo may cover a similar ground to hobio but when it come to derivatives the latter is more convenient - hobiista, hobia, hobieca, hobiaĉo ktp.

There is also an expression amata ĉevaleto which I think refers to something that someone has a bee in his bonnet about, likes to talk about.

If someone is, say, a historian with a special interest in the medieval period then I think 'speciala/aparta intereso pri' covers that.

I wonder if 'hobio' can't be sometimes a little disparaging. If someone had an interest in the Stockmarket, would he be happy to have that described as his 'hobio'.

Breeding the perfect English Rabbit would however be a 'hobio' in my book.

'Libertempa okupo' offers a further nuance in this area.

Knowing NPIV and its love of French-based neologisms, I hazarded a guess that "maroto" is based on a French word, which would be "marotte", based on how French words end up in Esperanto.

Indeed, a French dictionary tells me that a "marotte" is a hobby. So I think that the NPIV editors lifted that one straight from French, as they are wont to do.

I've never heard it used though. I wouldn't understand it, even in context, if someone used it.