Well, like texmati said, Dallas is very conservative, but it can be quite tolerant. Homeschooling is legal and you do not have any required testing or even declarations to the authorities, midwifery has never been illegal (not even lay midwives). You can buy organic food almost everywhere. Baylor Medical Center in downtown Dallas is very welcoming of natural birth--much more so than the hospital that I had my oldest in the more liberal east coast. So while you will not find a lot of crunchy people here, you will find that it easy to have a alternative lifestyle than in a lot more liberal places.
As for the climate, you can consider that you will have about 9 months of summer, but it does get cold in the winter (you will need both heat and air conditioning, and don't throw away you coat and gloves!
). It is very flat here--I live in North Dallas about 15 miles from downtown and I can see the skyscraper from downtown on my street! There are trees in Dallas at least (although as you get closer to Fort Worth, it becomes more prairie like; it is for that reason that Fort Worth is considered the beginning of the west). When a storm comes through town, it is scary! It's like there is no place to hide. Tornadoes strike every so often, so if you hear an air-raid siren, you need to listen to the radio to see what's up (except when they practice the siren, which in my neighborhood is on Wednesday at noon).
So good luck with your decision. It took me years to get used to it here, and even now I'm not crazy about it, but it's a lot more tolerant here of alternative lifestyles than in most places.
