I'm schizo when it comes to our CRs. I pull from this site all 3 for both DW and I twice monthly. I like to see the cause and effect relationships, score-wise. For monitoring, I opt for TrueCredit (TC). Seems to work well. For added assurance, I pull hard copies of each CR directly from each CRA every other month or so.
There is no harm in checking your CR.
Don't dispute unless you have proof of re-aging. Look for old receipts, cancelled checks, even old reports. Disputing old accounts can cause their deletion which could lead to a score drop (even with lates and derogs present). If paid, the best option would be to send them a GW. You may be able to also ask for a payment history/record, etc.