Newbie Embroidery Questions

Hello everyone!
I just bought myself a Brother PE525 embroidery machine for monogramming and personalizing the clothes I sell on Etsy.
Here is the link to my Etsy store:

https://www.etsy.com/shop/LittlebitBowteek?ref=search_shop_redirect

As you can see I offer personalization on my outfit sets and a few diaper bags. I am brand new to embroidery and I have tested my built in designs twice. Here are some problems that I am running into:
1. The first time I embroidered an A onto a plain bib, and it was way to the left although I made sure that my fabric was centered on the hoop! Does the machine not start in the center of the letter? And if not for various designs how will you know where to start them so that they are in the exact place that you want them to be?
2. I have found the craziest thing! My designs seem to be backwards. When I look at the front it is less filled in, and it looks like the back but when I flip the design over it is pretty like the top should be. Do I have to place my fabric face down?
3. The second design I did I used a towel. I am using the white thread that my machine came with and on the top I couldn't see if it was doing anything, so I waited for it to finish and then looked it over. But when I looked at it it had only sewn a tiny bit and nothing more, and the bit that it did sew was backwards with the visible part on the bottom.
4. I am going to try to embroider a diaper bag soon, and I was wondering if ya'll had any advise on that? What stabilizer should I use? will I need a spray adhesive? What if I hoop a seam, will that matter?

Thanks for all of the help, and any comments would be appreciated.:)
Rebecka