1)他兒子今年6歲,按現在進展估算,21歲前拿到的可能性有多大?
-Very big chance.
2) 是否弟弟就不能以後再申請旅遊簽證了?
-It is fine for him to get the B2 visa to visit you.
3) 是否影響他兒子申請學生簽證?
-No. Your I-130 is irrevant to the kid.