Q#1 - I doubt the GERD is related to the surgery.
Q#2 - Why are you taking the digoxin? There may be a small risk of taking digoxin with calcium containing antiacids such as Tums but you can take any non-calcium antiacid such as Maalox tablets. Prilosec is an expensive but good alternative. Another option would be a H2 blocker such as Tagamet or Pepcid.