The abdominal scar you have from your childhood surgery carries a possibility of interfering with proper healing from a tummy tuck but an assessment of the area would provide better information. It is a benefit to you that the surgery was so long ago. I encourage you to meet with a board...
I have patients wait 6 weeks prior to resuming work outs after tummy tuck. The area can remain firm for many months though as there is always inflammation after surgery that takes that time to resolve.
I routinely perform liposuction on greater than 90% of my tummy tuck patients. It is safe to do so long as the surgeon is appropriately trained and certified.
