Yes, you get every single reward below your level. For example if you pledge $100 you get every prize up to that level.
We had some issues since we can't change the wording on the reward tiers. We apologize for any confusion.
YES! All rewards are retro active.
For EXAMPLE: You have pledged $150 but then a new awesome reward just showed up at 50 bucks. Do you get that new reward? YES, yes you do!
Don't see the answer to your question? Ask the project creator directly.