1. Compared to the feudal serf, the wage worker is more free in a straightforward sense. How? And also more free in a sarcastic or ironic sense. How?
Free from feudal and guild restrictions, free to move from place to place and job to job and sell his or her labour-power to the best buyer; but also 'free' from their direct access to the means of production (the serf's patch of land) and from 'all the guarantees of existence offered by the old feudal arrangements'.
2. Marx argues that the rise of the capitalist farmer and of the industrial capitalist involve different stages and factors. Which different stages and factors?
Note first that in these chapters - and nowhere else in Capital - Marx states that he is writing specifically about England. Other countries show different paths of development, sometimes very different.
The capitalist farmer, writes Marx, emerges by differentiation within the decaying feudal structure of agriculture. 'The first form of the farmer is the bailiff [the landlord's estate manager], himself a serf'. Gaining strength, he becames able to make a commercial contract with the landlord instead of just being his servant. As serfdom breaks down - which it did in England after the Black Death of the mid-14th century hugely strengthened the position of the surviving peasants against their lords - the peasants differentiate, some becoming capitalist farmers, some becoming wage-labourers.
The industrial capitalist, however, does not generally emerge from within the guilds in the cities. These guilds were associations of small workshop masters in various trades which regulated who could practise those trades, and at what prices and standards. Young boys would be apprenticed to a master, go to live in his house, and hope eventually to rise to become masters themselves.
Meanwhile, however, huge accumulations of wealth were acquired by merchants and bankers, from long-distance trade, money-lending, plunder, and slave-trading. Once the world market (with sufficient technology for substantial sea-trade) and vast masses of propertyless people were created, a portion of those accumulations was put into capitalist production. 'The new manufactures were established at sea-ports, or in inland points beyond the control of the old municipalities and guilds'.
3. Why is it only half-true to present the rise of bourgeois society as a battle for liberty against feudal and guild restrictions?
Because it is also a story of the dispossession of the peasants and of colonial plunder. Marx emphasises this because even the best of the economists of his day tended to see capitalism as the natural form of human society. Adam Smith, for example, starts his great work, The Wealth of Nations, by saying the propensity to trade and do deals is the defining and fundamental trait of human nature. That propensity generates the division of labour, then further trade, then further division of labour, and so on. Free-trade capitalism is the ultimate working-out of that propensity. In previous forms of production it was stifled by ancient customs, religions, superstitions and so on. Thus, as Marx put it, for them 'there has been history, but there no longer is any'.
4. When did capitalism first appear? In what ways was it then not fully-fledged?
First in the 14th and 15th century, 'in certain towns of the Mediterranean', as Marx puts it, presumably meaning principally Florence, Genoa and Venice, then more extendedly in the 16th century. At that point it was only the 'formal subjection of labour to capital' - i.e. capital, often primarily merchant capital, dominating labour-processes which were still mostly handicraft. It became the fully 'real subjection of labour to capital' only with the Industrial Revolution. (See part 14, chapter 16).
5. Were there capitalists and capital before capitalism?
Yes. As soon as there was an extensive money economy - and long, long before capitalism - there were merchant capitalists and money-lending capitalists. Given the erratic and unsystematic character of trade at that time, merchant capitalists could very well get rich by buying cheap in one place and selling dear in another. (The most important form of trade in pre-capitalist societies is often long-distance trade in luxuries or highly specialised goods). Money-lending capitalists could get rich by lending to merchants and to kings and lords who would pay them back out of their feudal incomes.