Could someone please answer the following? For tax itemizing regarding used household items for donations (clothes, shoes, books, curtains, etc.) how would I add them? Add the actual amount I paid for them in the store or add how much I think they are worth now? And when I get my total, what would be the actual percentage from the total that I would actual get back as a refund? Say if I were in the 28% tax bracket. And is there a minimum amount that I would need to donate to get a refund towards my donations? Also, is there a maximum amount that I can donate without creating any problems? Thanks.

You will itemize only when your itemized deduction is more than the standard deduction.
The price that buyers of used items actually pay in used clothing stores, such as consignment or thrift shops, is an indication of the value. By donating all the mentioned items, you should have deduction around $100.
Before actually taking deduction on your tax return, you must read IRS Publication 561, Determining the Value of Donated Property.

If you value the donated items at more than $500, you must use Form 8283 to provide detailed information as to whom you donated the property to and how you determined the value of the property donated.

A large non-cash donation (say something in the $10,000 range) will almost certainly get the IRS' attention and may result in ana uadit notice asking for more details about the donation.