iPhone newb, need sggestions for: case, BT headset, & apps please

I've had my BlackBerry for over 2 1/2 years and really liked it (still works great) but decided to finally switch to an iPhone.
I ordered an iPhone 4 last week and received it yesterday. All I've done so far is charge it. I know almost nothing about it other than everyone I spoke to says they "love it".

There are 3 things I initially need help with: case, BT headset, and Apps.

case: I have a great case / holster for my BlackBerry that I bought from Seidio, it was around $50 (little pricey, but not bad), but it has done a great job of protecting my BB and the holster is convient and easy to use. It's clear/hard plastic. Can anyone recommend a similar one for the iPhone 4? I'm not interested in anything flashy or the big rubber cases.

BT headset: I don't currently have one, so don't know where to start. Want something I can use in the car or @ work, and I'd like to keep it under $100. I've heard the Jawbones(?) are good. please recommend a make/model for me.

Apps: free is best, but I'm willing to buy any that are usefull to me. I don't have any aftermarket apps on my BB, the supplied ones have been good-enuff for me. suggestions?

a friend recommended and "Otterbox defender" case and also suggested I get screen protectors. Any specfic suggestions or links?

When I briefly had an iPhone 4, the case I liked best was Belkin Grip Vue. I think it's that TPU material - which has grip like silicone but doesn't collect lint as badly, looks much sleeker and glossier, and slips in the pocket easier. Best Buy had 'em for $20 but they were clear only, which actually gave a translucent white effect which I didn't like. So instead I found a dark smoky one on ebay for a little over $10 and iPhone 4 looked great with it. But this wasn't a holster setup. I prefer to carry my phone in my pocket so it was perfect for me.

The Jawbone Icon models look really good, and I liked that they used a standard microUSB plus had a physical sliding on/off switch. What I didn't like was the lack of volume control. They claimed their advanced sensors would automatically adjust volume correctly but I prefer having manual controls. I've always leaned towards the Moto headsets with the flip out mic. Easy to shut off and easy to tell at a glance whether it's on or off. Like the H17