Is my employer at all responsible ?

"Harassment" could mean many things. If sexual, racial, religious, etc . . . , it may require your employer to protect you. If safety related...

An employer can schedule you for as little, (or as many), hours the employer wants. There is no law regarding this in Texas.

Management bonus: can a company change bonus targets midyear which will apply for the whole year ?

That is a tough question that would require specific detailed analysis by a lawyer. Most likely it would be actionable as a promissory...

Can I sue because I missed a bill payment because they didn't pay me?

Probably, but difficulty is finding a lawyer that would sue for such a small amount. You could consider bringing the claim in small claims Court.

Can my employer call for Mandatory overtime with short notice?

An employer in Texas can require employees to work overtime.

Can I file a law suit if the company I work for is a hostile environment

A "hostile-work environment" is only actionable if it is motivated by al illegal factor, (such as race, gender, religion, etc . . . . ). The only...

Can I be docked pay if I'm salary exempt and was short 3 hours Monday and 2 on Tuesday for Dr's appointments?

What you are explaining does not make sense. An employer cannot pay you a salary and deduct for time taken off, (except under some very specific...

Do I qualify for over time pay if I worked a 6 and a half hour shift with no breaks?

Overtime only applies to working more than 40 hours a week. You are also entitled to be paid at least minimum wage for all hours worked.

How can I sue Walmart if I was terminated wrongfully and injured?

Not sure if you would have a viable illegal termination claim, but if you were injured on the job you could make a claim on that. It may be...

Can a company refuse to let you take a leave Day when you requested it a month ago and they approved it at that time?

I am not aware of any laws that prevent the company from rescinding your vacation request.