Verified answer

Yes there was trade, but it was often hard to implement. There was export ban on many technologies from the West into Eastern Europe, plus the West will only accept hard currency, which was hard to come by. The East also exported, but many items were not on quality that the West would accept. The trade was done usually through third country, like Yugoslavia, Finland, or Cyprus. During of the communist times, we had cola drinks, German candies, French cheese or Italian wines, but they were rather expensive and not affordable. Many countries also licensed items or sell industrial equipment. During the communist era, Japan build several electronic facilities in Czechoslovakia, Sweden had regularly exported machinery and Germany electrical engines. Eastern Europe often exported raw materials, gas, oil, ore, but from Czechoslovakia there were many industrial equipments, engines, spare parts, furniture, textiles, shoes, and glass. Some food stuff, like beer, hops, poultry, and sugar was heavily export oriented. In the 1980's, Czechoslovakia was one of the largest exporter of the sugar in Europe to displease of France and when EU was enlarged, majority of sugar processing factories were shut down. In years between 1955-1975, the trade between Eastern and Western Europe normalized, in the Eastern Europe, it was done through several state owned, export oriented companies. After 1975, the quality of products from Eastern Europe started to stagnate and became hard to sell. Eastern Europe was also desiring more for the Western goods, which created negative balance of payments between 1975-1990. The share of the West in the international trade decreased from 35% around 1975 to about 20% at the end of the communist era.

Of course!. Enoch Powell, for instance, the very right wing racist member of parliament had, when he was minister of health under Ted Heath, imported generic medicines from Poland for the British National Health Service to save paying royalties on medicines covered by US patents. The CIA even had to sabotage British trade with Castro's Cuba by sinking a ship load of Leyland buses bound for Havana in the Thames estuary in the early 1960s.

Officially no. However there was a lot of "bending" of the rules by importing/exporting through third party countries.