In terms of safety, the Houston area has something along the lines of ‘flood codes.’ Basically, when you’re buying a house, it’ll say the chances of that property flooding. So, there’s the equivalent of “Once every 100 years,” “Once every 500 years,” etc. My house (in central Houston) does not even have a flood code since it’s on relatively high ground. A lot of very nice homes are in areas near bayous which are very flood-prone. Your realtor can probably give you more information if you decide to move forward with this.
Like anywhere else, I think the most important thing is to stay off the road when there is flooding. Main roads and highways are prone to flooding (as you can see by some of the road signs in the Houston area). Last June, I saw a ton of abandoned vehicles on and near a main road running through Houston. Even with moderate rain, some roads will start to flood, so use good judgment.