Both sound fine to me depending on what your meaning is. For sentence two you might want to clarify what you want the reader to do exactly. Do you want them to insert the words into sentences already given or do you want them to compose/create two new sentences? Perhaps the following would be more clear: 2. Choose two words from today's list and use them in two new sentences.

Yes, both correct, but I would personally use - 1. Choose two words from today's list, and then write two sentences with your chosen words. 2. Choose two words from today's list and then reword them into two sentences. Hope this helps!