As for problem #1, are you pinch-zooming vertically or horizontally? That is, are you expanding your fingers along the long axis of the phone or the short axis? If you're expanding them along the long axis, you run the risk of touching the home button, which will close the browser. Make it a habit of pinch-zooming along the short axis.
As for problem #2, there are only 3 zillion possible explanations. Need to know more about what apps you've installed and are running in the background as well as how you have your phone set up for sync'ing data over the web. Clearing the cache of some apps (like the browser) can speed things up sometimes. Many times, a power down/restart cycle helps to clear the clutter and speed things up.