Should be fine. Fungus gnats and such are common when it is too wet but mixed in to the garden shouldn't cause any problems. Dave

Are these in containers or in a garden plot? If in a container there would be no really good reason to add garden soil since that tends to inhibit drainage in containers. If in a garden plot your soil is there and you need not be concerned about it. All the microorganisms you will need should be in the compost, unless it was sterilized before being packaged in which case it isn't worth anything. The nutrients in the Rock Phosphate and Greensand will not be available to plants this year since it takes those soil microorganisms several months to work on them and release those nutrients. If this is a container mix there was no good reason to add that material to the mix.

Maybe I'm cynical but I can't believe all bagged compost is the same. We live in a world where people put melamine and formaldehyde into food products to turn a profit. Who's to say that there isn't a bit of motor oil or something mixed in my bagged soil to make it look darker? There could be chemicals, less-than-well-rotted manure, weed seeds, chunks of wood and what-not in those bags. I saw bags that indicated thar the compost came from curbside pickups. That's very well, but I put into those pickups everything that I don't want in my home-made compost pile, and I'm sure others do the same. How do I know this has been properly managed to kill weeds or pathogens? At least here in my municipality I can go and see those piles steam with my own eyes. I don't believe that "more expensive is better" either, but I just don't buy that all bagged compost is the same, in the end. I think the only way to ensure top quality stuff is to make your own. Unfortunately, like some others here, I don't have the space to make as much as I'd like.

There is no need to do that. If aged animal manure is over 1-2 years, use it! Any risk of seeds still surviving in it is slim. However when you hot actively compost any form of nitrogen sources (like manures) aerobically with carbon sources (like straw or leaves), even within a few months, all potential seeds are digested and gone within. If you are still unsure, you can always re-compost the aged manure into a fresh compost pile with more greens and browns in it. The extra aged manure will add more organic nitrogen and beneficial microbes to the decomposing mixture for faster composting. Happy Gardening!