I don't have any experience with embroidery machines either, but having just reaserched buying one, I can tell you some of the things that have influenced me
First thing to consider is budget. If you want a sewing and embroidery machine, they are usually more expensive. If you just want an embroidery only machine, budget can be lower, but you need the space for two machines.
What you are describing regarding you guiding the fabric sounds more like free motion embroidery, which you can do with any sewing machine. Embroidery machines are fully automatic. You hoop the fabric (the hoop makes sure the fabric doesn't shift), select the design, push the button and the machine does everything else. Depending on the machine, you might have to cut some jump threads mid way.
I have only check Brother software so far. It can open .pes files and export into any other embroidery format. You can open files other than .pes only if you convert them first.
Machines with one needle will always stop for you to change color. There are also multi needle machines that will change the color without your intervention (use a different needle threaded with a different color).
Main differences are:
- max hoop size - the area you will be able to embroider in one go. This doesn't mean you will not be able to make larger designs, only that they will require splitting the design into sections that would fit in your hoop and rehoop several times. Bigger area is better
- speed - embroidery takes a long time
the faster the machine, the sooner it's done. A large and intricate design can take over 30 min to complete.
- screen - some have larger screens than others. This helps you see the design better, edit etc.
- embroidery designs - they all have dome included, but you can buy (or get free ones) as many as you want. Make sure the machine is capable of reading a usb stick as cards are getting outdated.
I bought the Janome Skyline S9 (Atelier 9 in the Uk). It's the machine that satisfied all my needs and was a decent price (decent when comparing to the Brother V7).
I needed a sewing + embroidery combo. Wasn't too worried about hoop size because Janome has some apps for easy rehooping and aligning, and the largest hoop is fairly decent (17x21 cm).
It also had sewing machine features I wanted (lock stitch, thread cutting, pivot function, knee lift, walking foot etc.).
When I need to make this kind of decision, I usually start from the top down. I look at the most expensive machines to see what they offer and then decide which functions are nice to have and which ones I really need. I then take a look in my price range and see how many of the above I can check. Depending on what's available, I might increase the budget if I consider it's worth it, or I might cut some things off of my "need" list
Hope it helps!