Bleeding with clots and tissues,due to low-lying placenta. Is this placenta previa?

Hello doctor,

My wife is 35 years old and first time pregnant. She got pregnant naturally. She is running into 18 weeks and five days as of today. No history of any fertility treatment ever. Last week, she had bleeding with clots and tissues (one pad soaked each time) twice in four days interval. We consulted a local doctor and had a 4D ultrasound scan. The fetus is without anomaly but she has low-lying placenta covering the os and a 14x8 mm retroplacental clot was observed. She also has cervical polyp but the local doctor observed bleeding is not due to the polyp. Along with total bed rest, the local doctor prescribed the following:

1. Injection Proluton (once so far),
2. Tablet Miprogen 200 mg twice a day for five days.
3. Tablet Texakind 500 mg thrice a day for five days.
4. Tablet Duvaldin retard twice a day.
5. She has a tendency of sinus and recently had cough. Hence, the doctor prescribed antibiotics also.

Questions:

1. She is still bleeding, though lesser in quantity (maybe 20-30 drops). Is the above medication enough? Do you recommend any change?
2. Is this officially placenta previa situation?
3. We want to fly back home on the 25th having one and a half hours flight journey. Is this safe? I read contradictory views on cabin pressure factor.
4. Are coughing and sneezing creating jerks contributing to bleeding?
5. Since last USG mentioned "covering the os", does it mean there is a very slim chance of placenta moving away from cervix os in the coming weeks?
6. Is this small but frequent bleeding fatal to the fetus? How to determine if it is time for blood transfusion?

Sorry for the long post. This is our first time and we are very anxious due to ongoing issues. Please guide us. Thanks.