Eileen as you develop in playing, you'll see there are a lot of little tricks or technics with both hands.
I do a lot of finger picking and strumming at the same time. I have 3 guitars but play my acoustic most of the time on an amp with effects.
Its not important if your not playing over the center or near the tail piece.The center gives a bolder sound.
I go back and forth for a mixed sound, but actually never really pay much attention to that. Its just where your comfortable at. It is important to use your finger tips in learning, otherwise you'll mute other strings.
If your practicing right, your fingers will get very tender. Push through that, even if they blister. Soon they will calise and pushing on the strings gets easier.
Do you have a tuner? Get one if you don't.
Most of the mini guitars you mentioned have a lot of tuning problems. Hopefully yours will be OK. I suggest learning on a normal size guitar. You'll get use to it and be surprised what your little fingers can do. All guitars have different size necks, some thick, some thin, some round, some flat. Go to a music store and see what they have.
We guitar players have gone through a lot of guitars. They come and they go until we find the one that you just have to hang on to.
Peace
Roy