If you are concerned about archival quality, do NOT use acidic items on your page. Acid migrates (or travels), so it doe not matter whether it's touching your photo or not. Over time, it will deteriorate.
Of course, there is acid in your skin, so if you are being "truly" archival, you would wear gloves while scrapping, which I doubt anyone does.
This is a personal choice.
I try to use mostly acid-free items on my pages. If I find something I want to use that is not acid-free, I will typically use it anyway.
Although, I will never use fun foam or construction paper, because that stuff will break down in a matter of months!
As for acid neutralizing sprays. My opinion is that they are extremely expensive and haven't been around long enough to test whether they actually work.
I figure that if a small percentage of my pages do not stand the test of time, that's okay, I have plenty of others!