Ahsoka is worth investing in, she's great in a Galactic Republic lineup late game.
Jedi Counselor and Talia aren't really worth gearing. You CAN gear Talia, but she's non-essential and personally I wouldn't invest.
Hyperdrive Bundle is a really, really good deal. Definitely worth it and worth more the earlier you get it, but also it IS a big purchase and you should probably wait until you're sure you want to invest in the game like that. Reminder that this bundle is one of the only ones in the game that is actually worth it. If you buy it, you won't NEED to spend much more on anything else if you follow advice and play smart.