Tithing? In response to the previous question, I believe grace giving has replaced tithing, and is a heightening of giving compared to the Old Covenant. For example, the motive is heightened to "God's inexpressible gift." Grace giving is one element of New Covenant worship, which is a heightening of Old Covenant worship. The essence of New Covenant worship is the presentation of our bodies as living, holy sacrifices. Such worship is again motivated by "the mercies of God" (Rom 12:1).
Recommended reading In response to the previous question, historical premillennialism is ably taught and defended in Wayne Grudem's, "Systematic Theology." It is also taught in George Eldon Ladd's Revelation commentary, "A Commentary on the Revelation of John." The "already" and "not yet" aspects of the kingdom are taught well in Thomas Schreiner's, "New Testament Theology," part 1, "The Fulfillment of God's Saving Promises: The Already-Not Yet." A briefer but excellent treatment is the chapter on the Kingdom of God in John Frame's, "Systematic Theology." For the relationship between Israel and the church, I recommend the section on Romans 11 in John Murray's commentary, "The Epistle of the Romans."
The role of an evangelist In response to the previous question, the term "evangelist" is used several times in the NT. Philip was an "evangelist" (Acts 21:8). Eph 4:11 lists "evangelists" with apostles, prophets, shepherds, & teachers as people given to the church for the equipping of the saints for ministry. Paul told Timothy in 2 Tim 4:5 to do the work of an "evangelist." A biblical evangelist is someone like Philip who is specially gifted and active in proclaiming the gospel to unbelievers. This does not deny that every Christian is called to evangelize. When people are saved under the ministry of an evangelist, the evangelist has a responsibility to lead them to become incorporated into a local church.