Romex and breaker switches

I did a search and have read previous posts, but I still have some questions. I had an electrician install dedicated lines in my listening room when we built our house 20 years ago. I bought simple hospital grade outlets from a big box store and did not specify the gauge of the romex or anything else. I need to clear out my dedicated listening room soon for new hardwood to be installed and figured now would be a good time to revisit and improve my dedicated lines. I have already bought a pair of Oyaide R1 duplexes and intend to have them installed side by side behind my equipment rack. My question is-is there a particular variation of 10 gauge romex that would be best? I have looked and there are quite a few variations including 10-2 and 10-3 and I have no idea what to buy or for that matter, if some other wire that would do the job and not be prohibitively expensive presents a better option. I will need a 20 foot run for each duplex. Also, can someone help me as to whether the breaker switch on my panel matters much and whether I should opt for 20A, 30A, or other? I now know that all runs from my duplexes to the panel should be to the same leg. I will make sure that happens. Any other recommendations or advice about romex/wire to use and breaker switches given my decision to go with Oyaide R1's would be most appreciated.