Ok
He was a Private First Class when discharged. His branch of service was Coastal Artillery Corps (Antiaircraft). A word of explaination here is that the coast artillery for some odd reason known only to the US Army was tasked with air defense prior to and during WW 2.
In box 5 it shows his status as Army of the United States meaning he was drafted and not a "regular" and neither a reservist, volunteer, or National Guardsman.
Box 7 shows his discharge date
Box 30 shows his official MOS as 650. This doesn't mean he actually did this just that officially that was what he was supposed to be trained to do.
The last three show his awards and campaigns.
Now, it is possible, and actually very likely that he was pulled from some antiaircraft unit in late 1944 (October to December) or early 1945 and used as an infantry replacement. This was very, very common in the ETO during this period as casualties had mounted and there was a very bad shortage of infantry and a massive excess of antiaircraft units in theater.
Given the three bronze stars this is probably the case. What you give here doesn't say what unit he might have been sent to but you indicate the 45th ID and 3rd Armored. This is entirely possible. Armored infantry battalions were some of the most cronically understrength units in the ETO much of the time due to their constant use in offensive operations.