Does one bargain with the vendors on this shopping street? I assume it's strictly cash only?
My map indicates depart station G19 on the Ginza line and use exi 1.

The Japanese don't bargain, but the tourist junk that they sell on this street is available at many stalls, so just compare prices if these are the things you wish to buy.

I think you will find that many of the places will accept credit cards.

All the items in those stalls/shops will have price tags. Some might accept credit cards if you are buying a lot, but yes, you'll need to bring Yen.

Bargaining is not normally done in Japan. Only place I can think where it might be normal is at flea markets.

The In Tokyo the only place I know that you can bargain is at the Ameyokocho market I mentioned somewhere earlier. Bargaining in Japan is not brazen as it is in say China. For example you need ask gently and politely if they will accept 20 yen for a thirty yen item if you buy five pieces or similar. Do not be mean or demanding or you'll get nowhere. Some shop owners will offer you a discount outright in the back stalls where the jewelry items are sold.

http://www.japan-guide.com/e/e3012.html

Its right outside the Ueno station and also a couple of subway stops away from the Sensoji Temple and the Nakamise Dori(street) you mention above so good to do those in one day if you desire. Ueno Park is also right across the street from Ameyokocho. Good luck! and don't forget to smile when bargaining

Aloha!

I forgot about the Ameyokocho market. Gentle bargaining may work there. It is like a permanent flea market!
As HT said, smile and be very polite. Best for bulk purchases or higher markup items like jewelry.