Both ideas have been regulary posted and discussed on the forum.
Transport ships that move your resources would overcomplicate the trade in the game. As you buy your goods anonymous in the market you don't know what country you buy it from. Secondly, countries like Canada or US would have a big disadvantage compared to European countries which wouldn't be fair. It would also take to long for your ordered resources to arrive which is not practical. There is a new concept of trade being tested now in the beta games that will be launched soon.
Mine layers: Great idea, for so far I have read there's a lot of players that are interested in this. It would definatly help to protect your coastline against an invasion. However as those mines would be invisible they would kind of be like unmovable subs. So we could just keep using submarines for the same function.
Naval Blockades have many usages in Call of War, mainly used for limiting a country's ability to launch naval invasions and simultaneously making a naval invasion by yourself not dangerous for your transport ships. Although these tactics were applied in blockades throughout the mid 20th century and WW2, Call of War does not simulate the ability of a country to stifle another's economy and army development. What I am proposing is that goods bought on the market would have to be shipped to a country via cargo ships, and disembark unto that country's soil BEFORE being added to a country's resource storages. These cargo ships would work essentially as Transport Ships, being lightly gunned and severely open to being destroyed thus best accompanied by war ships (if the country selling these goods sees this to be fit). This would affectively add the ability of a country to limit the amount of resources sold to an adversary (ofc w the ramifications of possibly inciting conflict w the country supplying the resources).