You are right that salvation is the first (and most important) thing a person should hear. However, I see two problems with the idea of not stressing the importance of the rapture and its significance in God's over-all plan.
First, we are not just commanded by God to evangelize the world, but to ALSO disciple it. Your have defined discipleship as, and I quote:
"we should testify, whether by mouth, by action or whatever means to teach the unsaved about the Glory of Christ and that He has died for them to."
Now, you have stated that this is to be done AFTER they have accepted Jesus as their personal savior ("once we have done that"), but what I have just quoted is a prerequisite FOR salvation; specifically "that He has died for them". If they are already saved, repeating this serves little purpose other than to remind them of His sacrifice (which is quite important), but because this is a prerequisite, it is not discipleship. It is instead repeating evangelism. Let us feed on meat and not milk. My intent is not to attack your Christianity, and I may have simply clarified what you were trying to define as discipleship in the first place. To that I do not know; but, as Christians, we do need to choose our words, as well as our battles. Let us be like the church at Berea who searched the Scriptures daily to see whether these things are so.
(Back to my first point again...) Because understanding God's Word (all of it including the rapture and eschatology in general) is an integral part of discipleship, how can we explain to an unbeliever the urgency of salvation if we ourselves do not fully comprehend it? We must understand what we are sharing or we will be unable to share.
Second, because every passage of Scripture is important for the consistency of the Bible's accuracy, it is important for us as Christians to diligently study to see which views of the rapture, tribulation, and millennium are correct and which are hearsay. To find a passage of Scripture which contradicts another passage would DESTROY the reliability of the Bible, as we know it. And if the credibility of the Bible is destroyed, so is our foundation in Jesus Christ. I recommend the book "When Cridicts Ask" by Norman Geisler. You can find it at CBD for around $18.00 I am not trying to plug a book, nor do I recommend books I do not own. I have found this book well organized and helpful and hope others will too.
-myself your servant for Jesus' sake