Blood sugar b4 and after eating

I don't have RH but as I understand it your pancreas reacts to carbs by overproducing insulin, that along with the exercise could cause your levels to go too low. So I think you need to test regularly so you can correct a low if you need to

That's a fine 1 hour reading assuming it's your peak.
What would be interesting with RH would be your 2 hour & 3 hour readings, trying to see if you hypo.
Strictly speaking a spike <7.8(140) is fine.

Yes, a bad breakfast.
Are you trying to find your spike, there is maybe a reason why you have got that reading.
1. You spike very quickly, as you would with glucose dumping. So your blood glucose levels are coming down.
2. You spike later, as if the amount of initial insulin response is smaller, but eventually your spike will be low anyway. So it could be still going up or levelling out.
To find the spike, you will have to be record readings before and every fifteen minutes for a few hours, and repeat and record.
There is the possibility that you do not spike high, but because of the insulin overshoot you get the symptoms and hypoglycaemic episodes this causes.