Yes and yes.

When you update an address with a bank (including Capital One) it gets updated on your bureau. If a collection agency pulls a new bureau and finds your new address, they've got ya.

And yes, a secured credit card will help you strengthen your FICO score and you can start to reestablish your credit.

I had some credit card debts; one is now stats barred another isn't yet. If I apply for a secured credit card, will collection agents find my address and harass me? Will it help me to repair my credit once the debts are off of my credit report after 6 years?