Welcome to the forum! It is great to have you. We look forward to dialoging with you to help give some perspective and insight, all for the purpose of you seeing where God is at work and joining in.
It was great to hear of your Japan connection, Did you know that a great new manga Bible just came out in Japan? You can check out the English version here.
To answer your question, in reverse order. 2. In order to be here this summer, you would need to apply ASAP.
But before doing that...
1. Yes, you could come longer, which would be part of the jTeam program. We are opening this up to "solo teams", so there is the potential for you to come. Sue wrote in a previous email about staying longer and ministering in-depth. That's great advice. Let me give you a brief explanation as to the difference between these two programs.
Envision: if you have cross-cultural mission experience and know that God is taking you to the field overseas, and now are trying to figure out where, with who and in what capacity, than Envision is the right choice. On Envision, you would "shadow" a missionary and see what serving in Japan is like by doing ministry together. But to be clear, Envision is for people who already have the "call" to the field.
jTeams: If you want to jump into Japanese ministry, culture, language and relationships, then partnering with a Japanese church through jTeams is the answer. This would give you an amazing opportunity to partner with Japanese Christians to help them reach their local community with the love of Christ. You would gain great insight into churches and the spiritual condition here. While doing this, Asian Access could also give you the info we would give you if you came via Envision.
If you would like to talk further, let me know. There are fantastic opportunities here, and Japan needs to see the live of Christ lived out. If God leads, we would love to have you. Sometimes replies on the forum is slow (our fault, sorry about that), but it is possible to connect directly via email, or Skype. If you would like to, let me know and we can talk more. If you would like to email me directly, follow this link and click the email link in the Contact Info.
Again, thanks for checking out Asian Access and exploring what God might be doing. We look forward to helping you discern God's call.