sackboy97
I'll try to answer point-by-point, but before I go to them I'll say remember to have fun and keep in mind the next mini is always better. This is to say, don't be discouraged and aim for perfection. Rather aim for fun and improvement. And you will improve if you stick at it, I promise!
1. Yeah. Some prefer painting in pieces, but assembling the kit is solid approach. I fully assemble 90% of models and only paint in parts on in some specific cases. Remember to keep an eye on those mold lines and clean them off at this point. It really pays off!
2. Yeah, this would be the primer phase. That being said I know a guy who hand primes everything with Abaddon Black and he paints awesome minis. Like, the guy has won competitions. I apply black airbrush primer (Vallejo) with a brush during winter and it works alright.
3. Yeah, shake the paints really well and then put a little on the wet palette. Then add water on the palette to get the paint thin enough. The amount of water you need varies on the paint you are using, so just experiment. You'll quick learn to see when the paint is too thick (won't run, leaves brush marks, uneven surface) or too wet (runs everywhere).
4. Related to 2. A base coat of Abaddon Black is not a bad idea in your case. Just keep in nice and thin not to obscure any details.
5. Here you have options. You can use the black undercoat as a shade and leave some showing. That is one way of doing it and can lead to nice results with really striking contrast. Other option is painting everything with the blue, so that the whole model is same solid blue and then add wash. This is the method a lot of people use and can give some nice results. The step of adding a wash to solid colour mini and seeing it come to life with the variations of shadow on the mini is a fun one. You can also retouch the areas with too much wash on them with the blue paint after the wash has dried for a cleaner look.
6. Sounds good.
7. They are good straight from the pot. You can also make washes from any paint, but using a acryllic medium is better that water for that use. Also you will trip over your shade pot at some point during your hobby. Usually it's Nuln Oil. Don't worry. It's part of the deal. And oh, black lining places like armour panels for shading is absolutely a thing you could try if you want. It gives for a more striking shadow than a shade. Experiment and see what you like!
8. Yeah, the texture paints are probably the ones that have some "sand" in them. You can just put them on the base with some small tool. Don't use your brush because it will be destroyed. You can then apply the wash to shade the base too when it's dry.
Hope these help!