Since your dad's tumor was causing an obstruction and was resectable, the hemicolectomy was a good thing to do. It is good that he only had one positive node, and no apparent metastases.
I am not a doctor, obviously, and I can't tell you what to think about the abdominal wall connection stuff. If you do some googling, you can find out about more it. One thing I urge you to do is keep you rational mind in gear while doing so, and don't get overwhelmed by stuff you read about survival statistics and what not that are very likely out of date. Don't forget that treatments now in regular use didn't exist 10 years ago, or even 5!
Now, the information that your and your dad REALLY need at this point is his tumor genetics, because that will affect his ongoing treatment significantly. At the minimum, his tumor should be tested by pathology to determine if it is MSS or MSI, and whether is has certain genetic mutations, the most basic probably being KRAS and BRAF. Google those terms to see what they mean. There are several different chemo possibilities, and which ones are selected depend on these genes, amongst other factors. He needs to mmake sure that this is being done right away.
It sounds like they plan to do what is known as adjuvant chemo when he heals from the surgery. That's a pretty standard course of treatment for Stage 3, and the idea is to try to mop up any stray cancer cells before they can cause trouble. I am figuring--and remember that I am NOT a doctor--that they might be talking about radiation because of the abdominal wall stuff.
Stay calm, educate yourself, and support your dad. Big hug to you!
F, 64 at DX CRC Stage IV
3/17/18 blockage, r hemi
11 of 25 nodes,5 mesentery nodes
5mm liver met out
pT3 pN2b pM1
BRAF wild, KRAS G12D
7/9/18 CT NED, 2mm indeterminate lung nodule
11/20/18 CT NED, Lung nodule calcified granuloma. Enlarged spleen.
12/20/18 Liver MRI 5mm liver met and 2 lymph nodes in porta hepatis
6/5/19 Triphasic CT LN and spleen normal, Liver node stable
6/28/19 Pause Keytruda, predisone for joint pain
7/31/19 Restart Keytruda