1. Do I need to take a ''kurs'' to write a Theory Exam, or do I just book a appointment for the exam ?
Yep. 30 hours must be completed, although if it's in English, many driving schools are willing to do it intensively for more money in less time. For instance, 6 hours is about the "norm" for 1-1 classes in Poznan.
2. I am still not comfortable enough with my Polish to pass it in Polish, Is there a possibility of taking this theory exam in ENG ?
Depends on the city. Most major cities and towns have it in English and German - however, sitting the theory test in a foreign language automatically requires you to have a sworn translator for both parts - to translate the instructions in the theory part, and to assist during the practical.
You'll also require a first aid course and a medical check in order to sit the theory test.
Oh, and you're also required to have had at least 185 days of legal residency in Poland before the test - counted from the start date of your residence permit. The rule may be interpreted differently in different offices - but this is how the law reads. You're also required to have a PESEL.