There are many options regarding printing equipment and software. If you are on a very tight budget (as I was when I started) you could start with a heat press, a small cutter (perhaps a Silhouette Cameo) and a good A3 printer with pigment inks. You can usually find a CorelDraw suite at a reasonable price. You can do pretty much any design work for printing and cutting for t-shirts. Welcome to the forums and all the best with your t-shirt business.