1. A good pair of black pants. Elastic waist will be cozy till about week 28-30ish then you are going to want a full panel because you cannot sit down.
Gap has some great options, I live in these.
2. Jeans, as mentioned above.
4. Long tanks & T's if preggo in the summer. You can get these at target, old navy or a maternity store, Spendid makes cozy things like the below. They need to be long so they will last throughout your pregnancy.