Yukata shopping in Tokyo and sandals

Hi, I will probably be able to have a short 1 to 2 day visit in Tokyo on the weekend.
I thought about going to Ueno, Asakuza where the temple with this huge ball that hangs from a gate is and to the Daiba island. Any chance in picking up a yukata at one of the places?
Or maybe somewhere nearby?
I am also interested in these straw sandals, but I don't know the name. I don't mean the ones that are made of wood. Does anyone know?

Also how could I get to Daiba best? I heard there is some kind of ferry from Ueno, does it operate often?

I thought about going to Ueno, Asakuza where the temple with this huge ball that hangs from a gate is and to the Daiba island.

Ueno and Asakusa are different districts in Tokyo:

Ueno:
http://www.japan-guide.com/e/e3019.html

Asakusa:
http://www.japan-guide.com/e/e3004.html

The temple you want to visit is Sensoji and the "ball" is a giant lantern that hangs from the temple gate.

http://www.japan-guide.com/e/e3001.html

Any chance in picking up a yukata at one of the places?Or maybe somewhere nearby?

I've definitely seen yukata shops on the Nakamise shopping street leading from the gate to the temple. You should be able to find something there although they're not cheap.

I am also interested in these straw sandals, but I don't know the name. I don't mean the ones that are made of wood. Does anyone know?

You are probably looking for "zori" made from tatami.

http://www.japanesekimono.com/tatami_sandals.htm

I don't remember seeing them around there but they may have them. Wooden ones are "geta".

Also how could I get to Daiba best? I heard there is some kind of ferry from Ueno, does it operate often?

There is a ferry from Asakusa directly to Odaiba. You could also take the train. See here for more details:

http://www.japan-guide.com/e/e3008.html