It is easier to use 1/2 inch diameter instead of 3/8 inch for tubing, siphons, bottle fillers, valves, everything. The 1/2 inch diameter costs just a fraction more than 3/8 inch diameter but it has TWICE the flow area. It makes a noticeable difference how fast you can drain a kettle or fill bottles.
Any statements you read here or anywhere that you must get this or that, or must do things their way is suspect. Go with the equipment you have and just start brewing. You can get more or bigger stuff later.
Enjoy it! If you like using Mr. Beer or building brew sculptures, extract, all grain, cloning or striking out on your own, go ahead.