>>6336655A ballpoint needle has a blunt end, so it can slip between the fibers of knit fabrics without tearing them. Just check a package of sewing needles to see if it's Universal, Ballpoint, Heavyweight, or whatever.
The presser foot is the part that holds fabric still for the needle, a walking foot lifts up during each stitch to move the fabric. It's used things that are difficult to sew on like thick, stretchy, or plush materials.
If you want a good sewing machine for cheap, I'd go with a vintage model. Look for a local sewing machine store and see if they can hook you up.
The new machines basically just offer more fancy stitch settings and a lighter weight. The old machines are built like tanks and can last basically forever if well-maintained. My old Singer lasted more than 40 years before a hard to replace part broke.
