Yeah, there's quite a departure from Zwingli to the Baptist or Pentecostal systems. You can perhaps think of Zwinglian doctrine as the germ, which gave rise to Anabaptism, and then much later culminated into what we hear confessed in Charismatic and non-denominational bodies. These bodies are really a combination of many movements, but mostly distinctive to Baptist, Charismatic and the Restoration Movement - but you can follow the trail all the way back to Zwingli (and also Arminius given their Arminian leaning - a reaction against High-Calvinism).
The reason why we can classify the non-denominational (Baptist/Pentecostal) system as belonging to the Zwinglian family is because of its radical views on Baptism and the Eucharist. Zwingli held that the Sacraments are essentially empty signs or rites with no real substance. He understood them as merely outward signs; memorialism. This was a very strong reaction against the Roman system - especially Rome's position on Transubstantiation and Ex Opere Operato (neither of which are not found in Scripture). Calvin was somewhat more moderate, and Luther more conservative. In a nutshell and very oversimplified, you can think of the Baptist, Charismatic, Pentecostal and consequently non-denominational systems as the end result of a more theologically liberal position - by this I don't mean morally liberal, but essentially, these systems have a low view of things such as Baptism and the Eucharist compared to other orthodox branches of Christianity, where the Sacraments occupy a greater importance doctrinally.
Dispensationalists - that's a great question! The short answer is: yes, they are. But again, often unknowingly - at least I was! Dispensationalism gained much popularity through the Scofield Study Bible, but its origin can be found in the Plymouth Brethren. This was a movement marked by its opposition to creeds, denominationalism and ordained ministry; it was a forerunner to non-denominationalism in our day. I don't think it's a stretch to say that the Plymouth Brethren introduced some peculiar doctrines into the Church. This was really a result of their unorthodox, and frankly, poor exegesis and extra-Biblical revelation. Think of it this way: A group of people break away from the Church (as a reaction to the perceived dead formalism) to study the Bible in isolation - that is, very far removed from historical Christian exegesis. Dangerously so. Add to this their claim of new revelation or a new understanding of what Scripture means. These things gave rise to new ideas that gained popularity among other free-bodies, and one of the most common doctrines we have as a result is premillennialism; which is widely popular among non-denominationals, and really much of mainline Western Christianity. It's true that some early Church Fathers had Chiliastic ideas (believing in a literal 1000 earthly rule of Christ), but it's important to note that they are very different from what we find today - things like Left Behind etc.
In a word, dispensationalism and contemporary eschatology, though increasingly complex and varied, is very commonly held in the non-denominational bodies. It's not always emphasised to the same degree, but it's certainly something that is lingering in the back of their theological system and does shape their ministry and their understanding of what the Church is - especially in relation to the nation of Israel - but this is felt much stronger in Pentecostal and Charismatic bodies. The New Apostolic Reformation (NAR) is a very extreme example of this. Perhaps we could say that dispensationalism is a bit more diluted in the non-denominational system; it's often not systematically or explicitly taught, but more something inherited and taken for granted.
