Okay so let me start with apologizing for any out-dated, wrong, or kooky information I may have... it's been 10 years since I've been in the fish world, and that was when I was 15... so, I could use any help I can get x)
I do work with a guy that's very into the fish world - he has many different sized tanks of shrimp, just plants, fish, etc and I've gotten a lot of information from him, but I just want a broad range and to also find out if anything has really changed in the last 10 years or not lol.

So another coworker is giving me all of their supplies for a 10 gallon, everything except a stand, heater, and a fish net of all things haha. What 'everything' means, I'm not sure yet since I'm at work right now and everything is in bags in my car. Once I get home, I can probably put up a list of all of the things I have to see if anything needs changed. I do know that it was an established tank for over a year, but I don't know if that means anything for the equipment.

I plan to keep the aquarium in a corner of my room now empty after losing my pigs, by a covered window. I know exposure to natural light in a glass tank can build algae, but I'm not concerned with that really.
I'm going to get a stand this weekend and get the tank set up, but I've heard mixed information compared to what we used to do, so this is the start of my questions!

Cycling
We never really let our tanks cycle more than a day or two to let the dust settle from the gravel/sand, and even still, usually just put our fish right in after roughly 15 minutes to an hour of acclimation. We never lost a fish doing it this way, but now all of a sudden I'm reading things about cycling a tank for 6 weeks? Seems a bit extreme to me, but I know everyone has their own routine.

Water Changes
Again, we rarely changed the water in our tanks. I know the 100s got changed maybe once every year to year and a half, the smaller tanks maybe once every 6 to 8 months. We bred angels, frontosa's, and bolivian rams in a few of the tanks we had and they never suffered or passed from a lack of more regular changes. Now I'm reading smaller tanks need a water change once a week? The guy I work with only does 1/3 water changes every month in his smaller tanks and his seen fine.

Fish Compatibility
I've been told many things about compatibility with the fish I want to get and I know that at least two of the ones I want are going to be fine together - a male betta (probably a halfmoon) and a school of neon tetras. My coworker said that with a Betta being a top of the tank fish, the neons will be hanging around in the middle, that I could also have something like cories or a bristlenose. I definitely want some kind of bottom feeder/algae eater, so I was considering the siamese suckers since they're eat all kinds of algae and my tank is next to a window. My parents say that cories will harass the betta and neons, yet I see them on every list for compatibility with neons and betta. I know they can be feisty, but will they be a problem if I go that route? Also, I'll have gravel in my tank so I'm worried that if I get cories, will the gravel make their barbs sensitive? I really like cories and based on research, I really like the siamese too.

Overcrowding
This is the part I'm mostly concerned about. I'm familiar with the 1in per gallon rule, but I was also told by my coworker that it's flexible with smaller fish. He said that I could easily have the one betta, 8-10 neon tetras, and at least 5 cories or 2-3 siamese if the tank is heavily planted (which I plan on doing), but he keeps stressing a bristlenose (which I'd rather not have). I don't mind other suckers, I just don't want a bristlenose unless I can find a starlight for a reasonable price.

Plants, Decorations, Etc
I want the tank to look as natural as possible. The tank I was given has semi-natural looking gravel with what looks like blue gravel as well. Definitely not what I'm looking for, I'm more into the shades of brown gravel usually found in communities. I want a good amount of live plants, only supplementing with fake if I have to. We used to put fakes in the back and real in the front to cover most of the fake, but to also save some money on plants that aren't really seen. I'd love to put a piece of driftwood in there, as well. Mostly, I just want to make sure that the betta, neons, and whatever else will all be happy. I've done a fair amount of research on the fish on the internet, but I'm not wholly comfortable trusting an article over people's opinions and experience. I'm the most worried about using gravel with cories or anything with feelers as I don't want them to get injured from the gravel, but I'm definitely not interested in using sand unless it's better for the fish. I know that neons like to zoom around things and love things like moss balls and short grasses, but I also like not being able to see my fish 100% of the time, so some ideas on plants mostly would be amazing!