HI & Welcome!
You are asking great questions. Here is how I look at those price difference dilemmas in life. Consider how long you will have and enjoy the machine. Price it out by price per day. It is usually pennies so get the one that will use over cutting cost corners.
I invested in the machine with added features so I could grow into them. My machines are used every day. I love having the speed control buttons on the Crescendo and Brother Dream. I will always want to have a thread cutter and needle threader on my machines.
Re Question # 3. Do you have any thrift stores in the area? Look for a sturdy table that can be used or modified to your needs.
Good luck on your decisions!