sir, as per my assessment, the car has went through a cheap restoration with sole purpose to get good bucks from an un suspecting buyer. This is usual practice with some denters having side business of car sale/ purchase and some car dealers. Even sellers also think of getting make up on their rust buckets to get good return.
if you just want to mask the damage, then it wont cost u more than 3000/4000 for the complete job.
However if u want to keep the car then prudent approach would be;
1-assess the condition ( get an advice from trusted denter or expert
2- get an estimate to fix al the issues, it might involve scrapping the whole car or maybe a few penals, all depends upon the assessment made by denter.
3-making cost benefit analysis
its very difficult to assess just on the basis of few pics. Experts can tell after physical examination.