Downloading iOS 6 onto my iPhone 4 (8 GB)?

I want to install iOS 6 on my iPhone 4, but I need to have 2.5 GB of available data space and I only have 2.1 GB available. If I delete apps to clear space so that I can download iOS 6, will I be able to put them back on my phone afterwards? Or does iOS 6 permanently take up 2.5 GB of space?

IOS 6 will ruin your iPhone, google it and you'll see why.