Legal Question in Employment Law in Texas

Your best bet would be to form a non-profit corporation. It isn't expensive (about $75 plus whatever a lawyer will charge you).

Yes, multiple churches can operate under the umbrella of a single non-profit corporation.

You have to be careful that the corporation doesn't actually engage in a business for profit.

As far as keeping your church in "good standing," the rule is: a duck should walk like a duck and quack like a duck. Churches have meetings (though they may not actually own or lease a building) and they engage in "church work." As long as you're doing "church activities" you probably won't be accused of being a "sham" or a fake tax shelter.

There aren't any hard-line/bright line guidelines for what is and isn't a church. The government (operating within the limits of the First Amendment) doesn't get into the business of defining what "religion" is.

As for the rules about tax deductability, you should talk to a good CPA. The IRS rules can change on short notice.