replacing stock camera app

The stock camera app can probably not be deleted unless your phone is rooted. But you can use any of a plethora of camera apps in the Market (free and paid). You could look for them...
Read the promo blurbs, try out a few, uninstall what you don't want, and keep and use the one(s) you like.

My favs are Camera360 and HDR.

 

+1 for camera360

 

Do these apps just add borders and effects to the photos? i would love to take shots with a quicker shutter speed or even an anti shake/vibration...so many photos are blurred on camera phones

 

I use Vignette. It's very good with regular updates. Not too expensive either.

 

+1 i love this camera app. I was actually able to take a pic in a car moving of a motorcycle moving and nothing was blurry.

 

Uninstall, reboot, reinstall?

 

No.
You need border-, frame-, or FX apps for that.
Camera apps take photos and videos.

Holding (phone)cams at arm's length is a surefire recipe for blur.
Use support to mitigate blur.

(Free) Camera360 has an anti-shake function.

 

I checked out that Camera360 app, and is is quite nice. But holy cow, almost 7mb and you can't move it to the SD card.