It would be fairly safe to assume that whoever will be buying you your tank as a Christmas present will be looking at an all-in-one set-up, where the tank comes with all of the necessary equipment.
There may well be a further temptation to go as small and as cheap as possible, (money's too tight to mention, etc.), but this will be frustrating and actually quite limiting, if you were considering this to be your serious hobby. Smaller tanks are not only harder to stock, but they're actually harder to maintain than people realise.
You've made a good first step in deciding to research the fish and you're correct in noting just how many there are to choose from.
However, this and most other forums will be asking you about the chemistry of your water. Understanding this is key to you successfully keeping
any fish and so the advice given, to check with your water supplier as to the chemistry of your water supply, is well made.
You'll be picking up that there's a lot more to fishkeeping than simply looking at pretty fish in a glass box and you'll be able to make a better argument for a quality set-up, if you can demonstrate to those with the purse strings that you have really thought it through and you know full well what you're taking on.
Of course, knowing your local water chemistry will also narrow down, to some small extent, your choice of available fish, so you don't waste time chasing after fish that would be unsuitable.