ABS will last longer, has a higher melting point and is easier to sand and shape post print.

There are plenty of free or paid for packages. I use Simply3D, which is quite expensive, but well supported and easy to use.

The plywood frame is robust and fairly rigid. There is a limit to accuracy and layer height, so don't expect miracles at this price!

3D printing is a skill and you will find there is a learning curve to getting the best out of the printer. Don't expect a perfect print the first time you hit the go button!