I am very comfortable doing muscle repair and tummy tuck together. However, when a hernia repair is involved, I bring in an expert who does hernia repair every day. All plastic surgeons have done hernia repairs during their training, but general surgeons do them every day and I believe they will do a better job.
Complications are very rare, in my experience. The most common is a fluid collection called a seroma, which will not happen if drains are used after the surgery. A young person like you should be fine, but smokers and people with bad circulation can have loose skin after a tummy tuck. If you smoke, you should stop 5-8 weeks before surgery.
Generally, combining more than one surgery does increase the risk of complications. However, combining tummy tuck and hernia repair is a common and safe operation when done by skilled board certified surgeons.
Complication rate should be below 5%.
See befrore and after photos of tummy tuck: Set 1 and Set 2