First of all, thanks for all the help this form. Since I got my passport back I'd like to share some reminders first for the interview. The interview went pretty well, but we encountered some problems that caused 3 weeks delay. First problem is, for join sponsor tax problem. My wife's dad filed a joint tax for his family, even if her mom doesn't work she still need to fill I-834A form. I didn't prepare that one before the interview and the officer asked me to mail the stuff they need to them. Then comes with the second problem, I mailed through CITIC bank I thought this time I don't need to attach a cover letter so I wrote all my info on the envelope, then my package got bounced back after a week. I knew during the last step you have to attach a pre interview cover letter for mailing the documents cuz there is instructions in the mail but this time they didn't tell me. I felt weird wrote my info on the envelope when I mailed the stuff. However I didn't double check on their website. There is another cover letter that used for mailing additional documents after the interview. That's the two problems that people might have as well for their interview as well.
Ok now I have several questions about my situation that I would like people who know this situation can help me out. Basically for immigration under 26 they need to register for the military thing. I'm 25 now and will be 26 at Dec this year. My wife and I are going for a really long vocation at Europe and Costa Rico. The problem is I will transit in US when fly to Costa Rico from Spain 4 or 5 days before my 26 birthday. I know for US even if you transit you still need to process the immigration stuff. Does that mean I should hand off all my immigration stuff to the officer at that time? Or I should do after my Costa Rico trip back to US officially? Do I need to register for the military thing if I transit 4 days before my 26? How does that 26 count? The time you you got your immigration visa? The time you get your green card? The time you transit in US? The time you 'official' enter US? I've heard if you forgot to register or you trying to avoid register will have some problems when you do naturalization. But at the same time my wife is kinda scared of this military thing. She doesn't want me to involve any kind war. How does this thing exactly work? Also should I pay the green card fee right now or when I get to US? There is another Social Security Card problem that I need to take care later. Seems like there is a lot of stuff need to be take care of after the interview
Thank you all