All these are good advice.
However I would recommend you stick to plastic for learning. I know some would disagree and say it doesn’t matter, but I just feel that plastics are better for learning.
If you do get a new Velocity, it will not be Starburst response. With my Velocity (and you may be able to find the posts on here) I did have trouble with it being completely unresponsive out of the box, no matter the level I adjusted it. This has to do with the fact that a lot of YYF bearings are sold almost completely dry (little to no lube). So if you do pick one up you may want to also pick up some lube.
As for the string, if you can spring for it definitely go up to the 100 count. You’ll need it in the long run no matter what, and it works out to be much cheaper.
Someone once gave me some (I think) good advice. He said to improve your skill start with a Wood Axle Yo-Yo and work your way up to as far as you can go with it. Once you’ve hit the ceiling with it, move to a Transaxle. And then finally on to a Bearing once you can’t progress any further. All the while stick to narrow gaps and thinner bodies (modified shape not necessarily butterfly). This advice is basically built on the idea that if you can master a trick on a Wood Axle with a Narrow Gap, you’ll be a natural once you move up. This advice may not work for everyone of course.
As for a good starting yo-yo, I’m biased. If you were not to take the advice above, I think the Freehand is a good starter that can carry you a long way. It starts responsive, and you can tweak it later to become unresponsive as you grow. But that’s just me, I prefer it to the Velocity. Another good starter that you can pick up at a lower price (if that is an issue) is the Duncan Dragonfly (cheaper in response pads as well, the cork pads last much longer), but it will not take you nearly as far as the Freehand.