This all seems like truly sensible and professional advice, but is perhaps overly cautious. I'm still deciding, but the professors I've spoken with have uniformly said that it's more important that you think deeply and consider all your options than rush to let places know. I'm sure the DGS might get a little butthurt when you decline, but everyone else is going to understand (and in fact expect) that you need to go to the best school for you.
Yes. I'm still unsure as to when, because my March is hectic and their spring break interferes with my best week. Pitt isn't far though, so I'll definitely be going to check it out sometime soon.
Don't know if this was answered, but there is no general status check page. When they make a decision, you access your application and above where it says "Verify Address" will be another field labelled "Status Update" with a link to your decision letter.
They haven't updated mine yet this year, but I'm assuming all acceptances went out. Rejections last year were updated in early March.