I think that the 16-16-16 mathematically is the same as 8-8-8, you just use half the amount of the product. The slow half of the nitrogen that is slow release could take several forms, like a sulfur coating or larger granules or a different source of nitrogen. Often a cheap 8-8-8, 10-10-10, or 7-7-7 basic fertilizer will have no minors added..things like sulfur, calcium, magnesium, etc. More expensive fertilizers will often have those added,some now even have humic products and iron is also something often added to the mixture.
So what ever fertilizer you use in a chemical fertilizer check the label to see what you are getting, and compare prices too. I would definitely check with nurseries, co-ops, and neighbors to see what is normal in your area for nutrient needs and the best sources for buying them.
This may not be possible for you due to limited space, but if you have the space I would work on things like cover crops, adding all sorts or organic materials and even include some commercial chemical products into an area for a year or so before planting.
If you are going to be planting seeds I personally would not use any commercial fertilizer before planting, but would add a top layer of soil suitable for planting seeds ( something that would hold some moisture and not form a hard surface layer), then after they were sprouted and had some true leaves start adding diluted amounts of nutrients in the form of starter fertilizers, and build from that. Maybe you can even start to add things that would improve the soil along with the plant nutrients.
It is not so much the number 16-16-16, or 7-7-7 alone that is important, but the amount of product used.
I suppose the big disadvantage of testing the soil yourself it that unlike a professional soil test there are no recommendations accompanying the results. Maybe it might be a good idea, being you are just starting to garden in this location and have no passed experience to go on, to get a professional soil test with the recommendations on how to improve the soil. It might save you from making some mistakes early on that will take a long time to correct.
