does cancelling my group health insurance negatively affect any future purchase of health insurance in texas?

Answer 1

First of all, if you have not yet canceled your group health coverage, don't do it until you have some other coverage GRANTED (not just applied for). The reason to hold off canceling is that anything that happens while you are between health insurance plans will not be covered - not by the old plan and not by any new plan.
If you have already canceled your group coverage, get other coverage right away. A good and inexpensive way to keep coverage is to go to http://www.wavehelp.com/short-term-medical-coverage.htm and read up on short-term medical insurance. You can get a free quote to see how much it will cost and you can buy online if you wish. It is a better deal than COBRA usually (don't know if you are presently employed or not).
In any case, do not go without "creditable coverage" (that is insurancespeak for good, major medical coverage) for longer than 63 days. If you have no gaps in creditable coverage of longer than 63 days, insurance companies are required to insure you. However, the huge catch is that they are not required to cover you at a reasonable cost - their "required" policy could be TEN TIMES as expensive as their regular policy. The reason for this is that most people looking into the required coverage have some sort of bad pre-existing condition and the insurance companies want to charge so much that you will not choose to buy the insurance.
So, keep yourself covered at all times with good solid coverage including doctors, hosptals, and prescriptions.
Having said all that, if you choose to ignore the advice and go without coverage, your future ability to buy insurance will be determined by your physical condition at the time. If you have somehow escaped having anything go wrong while you are without coverage, you will be able to buy robust new coverage. However, if anything has gone wrong while you were without coverage, you may be unable to buy at all or if you are able to buy it could be a diminished plan that does not cover your health conditions that are existing at the time.
Best wishes.

Answer 2

Yes. You will not be covered for pre-existing conditions when you do get new coverage.