Yes you can . Core strength exercise

Yes , suryanamaakar should be fine. Alongwith other mild yogasanaas . Would suggest if * u take care of your diet by consulting a diet councillor. *Brisk walking every day for atleast 20-30 min . *Core strengths have to be practiced. Backaches tend to develop after pregnancy. *Drink lots of water, seasonal fruits and avoid (traditional ghee laddoos ) that is given post partum. * Also u may take swimming once or twice a week. This should help.

Before starting any exercise regime get your abdominal muscle checked for Diastasis Recti by a qualified physiotherapist. It is always appropriate to start exercising core muscles after child birth. I would recommend start with Postnatal Pilates routine. Pilates focuses on Core musculature while strengthening your weak muscles and stretching tighter muscle groups. It improves posture and alignment of body. Pilates helps alleviating pain and stiffness associated with pregnancy and child birth.

Oinstead of surya namaskar  do some core exercises and make ur abdominal muscle strong

Best exercises post natal is Pilates start with basic Pilates holding for 10 Sec professing for 30 Sec and then advance pilates

Yes u can start exercise ,Suryanamaskar, Running n good diet will help u to reduce post delivery weight .

Consult with a physiotherapist who have orthopaedic experience for proper assessment and corrective measures.