In Hinduism, real economic development (artha) is wedded to religion (dharma). Only adherence to dharma insures enduring economic well-being. In other words, anyone who is irreligious in his or her efforts for material advancement will lose out in the long run. You can't beat the system. No one escapes the long arm of the law of karma.
What are the most important or defining Hindu practices or beliefs? I know Hinduism has a variety of religious expressions, but is there a central ritual or belief that is common to all Hindus?
There are many beliefs that are central to all branches of Hinduism. These include the belief in reincarnation, and the belief that there is a categorical difference between the body, the soul-consciousness, and matter. Hindus also believe in the revelatory nature of scripture, and that all life is sacred. In terms of practice, all serious Hindus concerned with spirituality cultivate selflessness and chant or hold reverent the Holy Name of God. The sacred syllable OM is also a name or reference to God.
I go to temple to pray and was told not to eat meat before doing so. Why should Hindus refrain from eating meat before going to the temple?
Hindu saints and scripture recommend that meat eating should be avoided altogether because in the course of maintaining one's own life a person should cause as little harm as possible.
Overall, it is more harmful to kill animals for food than it is to eat a vegetarian diet. Grains, fruits, and vegetables are all lower on the food chain than animals and consuming them causes less harm. Although the scriptures state that all living things are conscious, grains, and vegetables are far less conscious of pain than animals.
For those unable or unwilling to stop eating meat altogether, Hinduism recommends that you refrain at least before visiting the temple or when on pilgrimage. Indeed, in sacred Hindu cities such as Pushkara and Vrndavana, meat eating is illegal. What saints are really trying to encourage when they advise against meat eating before visiting a temple is giving up meat eating altogether. This act of non-violence will greatly help one progress on the spiritual path.
Why is it that Sudras (workers) were not allowed to study the Vedas like the so-called upper castes or perform ceremonies in the Vedic way? Instead priests used Puranic verses for people of this caste and did ceremonies differently. I've done some homework on the subject and found that nowhere in the scriptures does it say a sudra should be initiated. How were sudras supposed to raise themselves above the level they had been born into if they were not allowed to study the Vedas?
Essentially the Puranas are different from the Vedas only in terms of the technical nature of their respective composition. Otherwise they are one, in that they are both of divine origin.
Chandogya Upanishad 7.1.4 states that the Puranas and Mahabharata are to be known as the fifth Veda. In Brihad Aranyaka Upanisad, the Puranas have been equated with the Four Vedas:
"The four Vedas, Itihasas, and Puranas have been breathed forth by that Great Being."
evam va are sya mahato bhutasya nihsvasitam etad yad rg-veda yajur-veda sama vedo 'tharvangirasa itihas ah puranam (Br. Aranyaka Up. 2.4.10)
The Puranas were written with the express purpose of making the spiritual essence of the Vedas available to everyone. In this regard, the great Gaudiya Vaisnava acharya (teacher/saint) Sri Jiva Goswami has compared the Puranas to the holy name of Krsna.
The holy name of Krsna is considered the essence of the Vedas and it is accessible to all. Those who chant it purely are considered to have mastered the Vedas. Skanda Purana states, "The holy name of Krsna is the choicest fruit of the vine of Vedic literature." As Krsna's name has not become less important or potent through accessibility, so the Puranas are not less important and potent on account of their being accessible to the masses. Indeed, they are the essence of the Vedic aphorisms explained through narratives.
In Vedic times, sudras were not initiated because of socioreligious considerations, but they were not barred from spiritual practice. We must be careful to make this important distinction between the religious and spiritual. Religious considerations govern this material world, whereas that which is spiritual transcends this world. In terms of spiritual considerations, in Bhagavad-Gita (8.32) Sri Krsna says that it is certain that sudras can attain the highest goal by taking shelter of him. There is no better way to take shelter of Krsna than by chanting his name.