European Options - Can I close position before Maturity/Expiry?

I have a question on European Options - Can I close position before Maturity / Expiry?

Since most of the Index options are European style so was wondering if I can close the Option before expiry. Say I bought Put option for SPX 500 when Index was at 3000 and in next few days if the index goes down to 2960, can I see my open positions (Put Options)?

Do I need to pay any extra amount at the time of closing my options assuming that I paid the premium at the time of buying Put options?

You can view what is on the bid/offer for your option & sell it anytime during market hours (before expiry). You'll have to pay a commission & clearing fees again regardless if you wait until expiry or sell it before hand.