Second day curls:
You are correct, this is for days you don't wash your hair. I'm probably telling you stuff you may already know, so sorry if something seems repetitive or telling you like you're five. And again, this is all just my experience and what works for me.
Most of the times frizz is caused by dehydrated curls, which is why conditioner is so important for us. Curly hair cannot handle being washed every day, even if you take a shower every day, just because of how fragile it is and that curls lack the ability to hold moisture, like straight hair. So, on days that you don't wash your hair, that's what people call "second day hair." I sleep with a satin pillow case because it's more gentle on curls, but even then, my curls look like crap in the morning - they turn two dimensional. lol So, on days that I don't wash my hair, I have a little spray bottle with just water that I wet them with to bring them back to life and then I add oil. I really like Jessicurl Oil Blend because it feels and looks better. However, you can use coconut oil, I used it for a while, but it's just not my favorite, my feeling towards it is meh. It doesn't seem to hydrate the hair, it seems to just sit on it and make it greasy and frizz up.
And you can keep going, third day, fourth day, whatever. This is the great part about having curly hair - our hair doesn't get greasy like straight hair.
Cream:
Cream is like gel, but they generally seem to have a softer hold, despite being heavier (as in, provides more moisture than gel). My favorite is AG Hair Recoil, but it's expensive so I never use it :D So, a cream is not necessary, especially if it's consistently humid. If you want to try a cream, just go anywhere and find something on sale (that's what I do, I don't know what's in my shower right now, I just know that it's curlyperson approved).
Another thing to note for short hair:
I don't know if you follow the whole curl-friendly guide, like not using products with sulfates, silicones, etc, but if you do follow that, with short hair, you'll need to clarify your hair once a month. Clarifying just removes build up. If you follow the whole no-poo thing and use sulfate-free products, then using a normal, typical shampoo once a month is all you need to do.
I just want to say I know this is a ton of information because we're not taught these things when we're young, so coming all at once is overwhelming. It's like trying to teach someone to cook who has never cooked. Your hair looked really good, so whatever your doing is working. It's just adding and modifying your routine here and there. What really helped me was reading the curlygirl handbook and then going from there learning and trying it out. Key points to really remember is just hydrate, hydrate, hydrate. Gel helps hold it together, but conditioner is the most important thing.