My son was older when he started - four. He is now fourteen. At the beginning, we had a couple of Pod errors that were very frustrating bc they made us think this wasn't going to work out. I found that we had to be really careful of placement - the Pods were bigger back then and when their bodies are so small it's much easier for them to get caught on something or, in our case, compromise the cannula. The smaller Pods help with this greatly. I would still avoid placement where the body bends - like the side of your torso. North/south placement on arm or leg and abdomen with the cannula positioned inward won't put strain on the cannula.
We were trained to prep sites with IV Prep. We found that weakened the adhesive. When we used alcohol only to prep the sites, adhesion was much better.
Remember that fast acting insulin acts very differently than long acting insulins. Both highs and lows can come on quicker, but you can also address them more quickly with corrective action. We find pumping requires more attention and more finger sticks, but we have more control so it's worth the extra effort.
We also found that Caleb's total daily dose increased significantly with pump therapy, as if for every unit of long lasting, he needed two of fast acting. He was using very little insulin pre-pump - less than two units - and was up to over 3 not long after pumping.
The day or two after pumping you will likely have some residual long lasting insulin from injection therapy, so don't be surprised if you start to see some highs during that time - you'll just have to reassess settings and adjust.
Keep coming back to ask questions as you think of them!