2. I like to improve my knowledge
2.I would like to go to the market
These are both correct- it depends on the temperature- 'cold' is more extreme than 'cool'.
It's hard to give advice on pronunciation with hearing the person's accent, but in general terms, you shold try to indentify the sounds that you find difficult, or ones that cause comprehension difficulties when speaking to people and focus on trying to improve them. Can you give me some more information- what pronunciation problems do you have?