I haven't grown asparagus yet going to next year but by googling the words " growing asparagus in Texas" brought up several Texas A&M articles for all of your above questions and a whole lot more that you will want to know before you plant your crowns. Good Luck and...
Happy Growing David

I grew asparagus at our first house. It was in a flower bed and very attractive! I think that yes you would need to compact your soil a bit, especially after tilling and adding compost etc. You can always count on whatever you plant to sink a little, unless you press down some on the soil before hand. With trees, I use my full body weight and press down around the root ball with my feet. But with asparagus, which I never got to see through to harvesting time, I would just use my hands to firm the soil. Especially since you should make little mounds in order to plant the crowns. If you don't firm it up, then you are right. They will eventually sink lower than they should be. Just like any other plant, especially mounded plants or plants in pots. imho that is what you should do with any plant or seed. Freshly tilled earthe needs to be pressed down in order to assure that the seeds or plants do not sink lower than wanted.

Good luck with your asparagus. Yum Yum!! My favorite because it tastes so good and because it is a perennial. I love the idea of perennial vegetables.

I have an asparagus bed. I kept adding more soil and compost materials every few months for the first summer. They are brown and dead looking now - I assume they are dormant, not dead. They did really well over the summer and grew from roots up to about 2 feet tall. This year I can do a little harvesting!
I don't think it matters much if you compact the soil or not. You need to keep adding more soil to your bed as the plants grow.

Here is a link that might be useful: how to plant asparagus