It's up to to to prevent from going over the limit and that includes interest and fees assessed, not just purchases.
Given the impact of Revolving Utilization (balance[s] / limit[s]) you don't want to have a high balance reporting anyway. 30% is the generally suggested maximum. If you were high enough that interest drove you overlimit then you were already too high.
Your creditor provides you with a card agreement when you receive the card that indicates how interest and minimum payments are calculated. There are interest calculators online that you can use to determine what the interest would be.
fansrancisco wrote:I have always paid more than is due and paid on time.
Paying on time is good. The minimum is just the least you have to pay to keep your account current. You need to consider Revolving Utilization and your limit as well. You need to aim to pay every statement balance in full to avoid incurring debt and interest.
fansrancisco wrote:Am I liable to pay OD fee?
It's not a checking or savings account so overdraft is not relevant. There are, however, potentially other fees. Read your agreement and understand it. That stuff isn't just packing material for the card. It's important information.
fansrancisco wrote:Am I able to ask Wells Fargo to retract the derogatory note on my credit profile?
You can always ask but they're under no obligation to remove valid information. Get that balance paid off and then try asking them for removal.