International trade can lead to significant alterations in income distribution within a country, potentially resulting in both advantageous and detrimental effects. Through the access to larger markets and specialisation, industries within a country that hold a comparative advantage may see increased profits and wages. However, sectors without such an advantage may face stiffer competition, possibly leading to reductions in income and employment levels. For example, in a country that specialises in technology due to international trade, tech industry workers might experience increased income, while those in the less competitive industries may face income stagnation or decline, thus widening income disparities.

An increase in consumer surplus usually implies an increase in consumer welfare as consumers can purchase goods at lower prices or access a broader variety of goods, enabling enhanced satisfaction and utility. However, it doesn’t always translate to overall increased welfare. When low prices are the result of compromised product quality or labour exploitation, consumer welfare might be affected negatively in the long run. Additionally, when consumers have access to harmful or substandard products due to trade, the surplus gained might not accurately represent an enhancement in overall welfare, demonstrating that the correlation between surplus and welfare isn’t invariably direct or positive.

Gains from trade allow countries to consume beyond their production possibilities frontier (PPF), which represents the maximum feasible amount of two goods that a country can produce. By specialising in the production of goods where they have a comparative advantage and trading, countries can acquire a combination of goods that would be unattainable through domestic production alone, effectively expanding their consumption possibilities beyond their PPF. For instance, a country proficient in producing textiles but not efficient in producing electronics can still access electronics by trading textiles for them, enhancing its consumption capability and living standards.

Specialisation in international trade can indeed augment a country's risk exposure to economic fluctuations. When a country specialises intensely in specific goods or sectors, it becomes increasingly susceptible to demand and supply shocks in those areas. For instance, a country predominantly reliant on oil exports, like Saudi Arabia, may experience substantial economic fluctuations with the volatility in oil prices. Such economies can be particularly vulnerable during downturns in global markets for their specialised products, necessitating diversified economic strategies to mitigate potential adverse impacts and ensure economic stability.

The distribution of gains from trade is often unequal among trading countries. Typically, more developed countries with advanced technologies and production capacities can secure more gains due to their ability to produce high-value goods efficiently. These countries often have stronger bargaining power in trade negotiations, enabling them to secure favourable trade terms. Conversely, less developed countries might not reap equivalent benefits, especially if they primarily export low-value goods and face trade terms that are not advantageous. For example, developed nations with strong pharmaceutical industries can benefit substantially from the export of high-value pharmaceuticals, whereas countries exporting primarily agricultural products may not secure comparable gains.