Firstly, let me say that I personally have difficulty dating squash blossoms. There are a lot of fine details that go into dating them, such as the clasp styles, and what they are strung on, and the weight of the piece. With the pics you’ve provided, I will do my best!
1.) Plain Squash Blossom: this is going to be a Navajo piece. Lots of sellers will claim that this plain style of squash is from the 1920’s or 1930’s, but I don’t that they are that old. The centerpiece Naja is sandcast, and has a slightly more modern look to it than the beads and squash blossoms. I think I would date this piece around the 1950’s, maybe as early as the 1940’s. The smoothed out bench beads and squash beads are all hand made, which is the key indicator that it is an older piece.
2.) Zuni Petitpoint Squash: this is a Zuni squash blossom. There is a thread on this forum that explains the difference between Zuni needlepoint, petitpoint, and snakeye if you are curious:
It looks like your piece has been cleaned recently. If you intend on keeping it, cleaning the piece is obviously personal preference. If you intend to sell it, I would let it tarnish. Most collectors I think prefer it that way. Unlike the first squash blossom, these beads are machined. The uniformity of the color in the stabilized turquoise would indicate that it’s a little newer. However, the workmanship shows that it’s probably from the 1960’s or 1970’s. It’s a really nice piece that I would wear myself!
3.) Santo Domingo (?) beaded necklace: I am not the best at identifying these. What I can tell you is that the use of the round beads throughout the necklace indicates that it is modern, likely post- 1990’s. Depending on the clasp, it may not even be Native American! If you can provide additional pics of the clasp and the turquoise drops it would really help! I’ve noticed that this style necklaces usually run for a pretty penny in the southwest 
4.) Zuni Petitpoint Squash Blossom: I think this style of squash blossom is nice because it uses bench chain (which is forged entirely by hand!) instead of beads, which probably made it a little more affordable for the original buyer. I really like the different colored turquoise here. It shows the age of the piece. Sometimes, turquoise will change color over the years after coming into contact with body oils. Seeing the clasp and a close up of the bezels of a few of the stones would help here. From this pic alone, I would say it was made in the 1950’s or 1960’s.
5.) Modern Navajo Squash Blossom: this technically isn’t considered a squash blossom, because there aren’t any squash beads on it! Lol. But for resale or descriptive purposes, we can call it a squash blossom. Each Naja and the Naja centerpiece are made using the sandcast technique. I would say that this piece was made post 1990’s. Replacing the squash beads with only Najas is more of a modern style of squash blossom. The turquoise looks like a piece of Kingman, but an up close pic will help further determine the mine.
Phew!
If you have any more questions, please feel free to ask!