Maybe I shouldn't even comment since I don't have the time to verify these things... But here's my experience anyway.
1. Texas residents often get licenses from other states. Reasons vary but include lower cost, less ridiculous requirements, protesting our ridiculous licensing scheme, etc.
2. You'll be able to open carry in a vehicle with a license. Without a license you cannot. On buses I have no clue - you mean like public transportation in certain cities? Or like Greyhounds?
3. I think that you are understanding it correctly, it is different than a requirement to "announce". The statute has more to do with requiring to produce IDs if they're requested, and with producing both your DL and license at that time. For instance if you are pulled over for a traffic violation and are CCing and the officer requests your DL, the statute seems to suggest that you should give him both your DL and license to carry, even though he didn't specifically request the license to carry.
4. People conduct private cash sales without an FFL.
If you end up coming - here's an early "welcome to Texas"