I'm sure it's an old Chinese silver box, and was made by a silversmith in Zhejiang, China. But to get more info to answer your other questions, I checked with an expert in China who have read a great deal of local history records, old newspapers and posts etc., and then gathered a lot of data about the silversmiths and dealers in China from 18c to 1940s. That's we got:
1) "浙省" (should read from right to left for old Chinese script), in this two characters mark, "浙" stands for "浙江" (Zhejiang) which is a province in East China. And "省" just means "province" in Chinese. The person I mentioned told me "浙省" is actually an abbr. of "浙江省城", and "省城" means the capital of a province. So this mark is a city mark for Hangzhou (杭州) which is the capital city of Zhejiang province.
2) We found a piece of record about the "盈源" (Yingyuan) company in Hangzhou which proved that Yingyuan was a manufacturer and dealer on gold, silver and jewelry, and existed in 1930s. But it can't tell when Yingyuan was founded.
3) "足纹" means pure silver or sterling as you may see on other Chinese silver items. The fineness is generally 90% or higher.
4) For the last mark "渭", it possibly the mark of a silversmith or a worker in Yingyuan who made this box.
Considering on the style of the box and the usage of "浙省" mark, it's very likely that the box was made in the ROC period, namely 1910s to 1940s (ROC is short for Republic of China, currently Taiwan, but except Taiwan province, it actually also occupies 3 counties of Fujian province and still elects their own governor of Fujian province).