[Sand showing Poop?]

It just means your flow could be stronger. 

[What is this in my aquarium?]

Problem is you used those seeds in conjunction with what you listed. 

[Aquaclear finally getting an upgrade?!]

I don’t find them noisy at all. It’s subjective. I have 6 in my living room and it works out great. I live in Florida where power outages are a common occurrence and I’ve never had an issue with it failing to restart, ever. 

[Finish Stocking 75G community planted tank]

How large is your angel?

[Fish unboxing tips??]

Don’t over think it, fish are more resiliant than we give them credit for. Everything you’re gonna do is perfect. Enjoy

[Fish unboxing tips??]

Is the tank heated? If not, letting them come to temp right outside your aquarium is adequate. 

[Moving five Black Neon Tetras - should I get more before moving?]

Definitely wait

[Waterproof dish/pad under aquarium?]

Personally I would never place an aquarium on a carpet that you can’t remove. Drips on wood are minor compared to mold on carpet. 

[Welp I nuked the tank…fresh start]

Swapping for fake plants will almost ensure you get more algae. 

[Shell dweller multi tank filter and stocking]

Sponge filters in opposite corners because it’s a wide tank. 

[Shell dweller multi tank filter and stocking]

Let me pose a question, do you want to see multie fry? Or you just want to keep the individuals you have happy? Danios could work but they are so zippy you’ll probably see a lot of dashing into shells. I wouldn’t add Tiger barbs to anything but a species only. It seems cruel to house a nippy fish basically hovering on top of each of their homes, jmo. 

[Shell dweller multi tank filter and stocking]

You could have dithers, endlers, guppies, platies, in a taller tank. In something that shallow, anything else you put in will get abused. 

[Waterproof dish/pad under aquarium?]

I have hardwood floors and I can be a bit messy so I always keep a towel on the ground near the tank I’m working on. Other than that, you’re overthinking it. 
PS congrats on your new home. 

[Turbostart 700]

If the sponge you’re squeezing isn’t cycled then you’re just making a mess. You need a seeded sponge to do this with. 

[Fluval 3.0 planted lighting specs and schedule]

I would stick to what you have. A Nicrew light would be a severe downgrade from what you already have. You may want to try either reducing the amount of time your light is on or you can experiment with floating plants. I would also toss some pothos hanging out of the top of the tank. This will also help with excess nutrients. 

[Turbostart 700]

The only way to seed a filter in 5 days is to squeeze a dirty sponge in that tank. There are no miracles in a bottle. The bottles may or may not help, a dirty sponge will work 100% of the time. Seems like an easy choice. 

[Aquaclear finally getting an upgrade?!]

Very true, I don’t see anything that really needs upgrading. Especially if it’s going to cost more. 

[Aquaclear finally getting an upgrade?!]

I hope they don’t mess this up. 

[Mineral Sunscreen]

Same with pine tar soap, it’s all natural and will definitely work. Or you can complicate this and bring gloves into it. 

[Cycle crashed and going on holiday]

Did you add fish food or some sort of ammonia source to the bucket for the filter to process? If you didn’t then your filter is most likely not seeded any longer. 
As for what I would do, you don’t really have that much time to do all the necessary steps. A more experienced keeper may get by, but this isn’t your scenario. I would see if my LFS can watch the little guy while you’re gone, possibly have them medicate it as well. I’d ask and bring the meds you want dosed. Or you can purchase seeded sponges from the LFS or a hobbyist and then you will have a cycled tank. I’d go for option 2, but that’s up to you. 

[Water is pea soup green with algae]

These are all great ideas if you have a willing person to commit to maintenance. Or else, you’ll be in the same boat with same or various other issues. 

[Starting a tank]

Lampeye kilifish would be awesome. Killifish jump, but I believe these do not. You can probably do 6 in there. I wouldn’t add much else though. 

[New tank]

I would add plants on Day 1, I’d also stay away from bacteria in a bottle. If you’re going to add snails or small fish, then skip the ammonia bottle as well. These just help complicate things. 

[Water is pea soup green with algae]

If there is no one willing to commit then you’re fighting a loosing battle. There is no quick fix. Either they commit or they have to deal with an eye sore. 

[New filter]

Buy the filter you’re going to use. A sponge filter never hurt nobody so I’d add one regardless.