In my experience, marigolds are pretty easy to start with. Water the dirt lightly, poke seeds a half inch or so into the soil, and they should be sprouting within a few days. You should be able to start them right now, I think, and they'll bloom until fall!
The other plants I don't have any experience with, but check the packaging for advice, and pay attention to your hardiness zone. Different zones have different windows for planting and growing. Depending on which part of Texas you're in, it could be anywhere from zone 6 to zone 9. It'll help you predict when the growing season ends, and with that information you can decide whether or not there will actually be enough time for your plants to grow fully and flower.