As for the sea trade, my understanding is that the Japanese couldnt trade with the Chinese (didnt have trade ships capable of making the safe voyage?), although they were interested. Basically each year a Portuguese ship (or was it a convoy?) would arrive to Japan and bring yearly amount of Chinese silk (Japanese really wanted all that silk), so this whole monopoly business deal was a huge source of income.
I think there were several direct and indirect ways of Chinese-Japanese trade.
1. Direct sail to Chinese ports. It was dangerous, not only because this naval route wasn't safe due to storms (East China Sea isn't Adrian Sea) but also Ming forbid private trade. On the other hand, direct trade with China meant high return and Japanese ships had actually enough capability to sail to the continent. Japan was a tribute state of Ming, and while this status officially continued very short, vassals of the Shogunate, especially the Ouchi and Hosokawa clan were allowed to send their ships in China. Of course other daimyos could trade in China privately, but it was considered piracy by the Ming government before the 16th century.
2. Trade with Ryukyu: Japanese ships went to Ryukyu, sold Japanese goods and bought Chinese and Southeastasian goods. It was a very popular route, and that's why Ryukyu was flourished in the 15th and 16th century.
3. Trade with Korea: Some Korean ports had Japanese quarter. Not only Chinese goods, but Korean goods were traded.
4. Trade in Hokkaido: Ainu people had their original route with the Asian continent. After the isolation policy in the 17th century, Chinese silks arrived from the North.
Also, Chinese traders (officially banned by Ming) lived in Japanese cities in Kyushu, especially Nagasaki and Hakata.
Wokou was an unique phenomenon, but it is controversial in the modern historiography of Asian history. While Chinese and Korean historians consider them as "Japanese" pirates, Japanese scholars point their multicultural aspects.