Quote: " I know that you can use C++ in agk and just looking at some sample codes of C++ on the internet it looks a lot like java. I have tons of experience programming robots in java, but never made a game. "
C++ is very similar to Java but it does require a bit more of the programmer e.g Memory Management and explicit pointers. The OOP is a bit different as well. That being said, if you have a lot of experience with Java then you should be able to make the jump to C++ without too many problems.
Quote: "So my questions are would I be better starting off in tier 1 or tier 2?"
To learn the workings of AppGameKit, Tier 1 is probably best but whatever is done in T1 can be imitated easily in T2 however. I believe the trial grants access to both T1 and T2 for windows so you can simply try them both out and decide which you prefer.
Finally, welcome to the forums!