>>9205853>1.Probably. In the long run 9V supplies are just going to get more and more expensive, and you can get the necessary Powered Up stuff for around the same price (The regulator/adapter together would be around $40-50 depending on where you look, and the contacts are a bit more expensive at like $30 for one with a decent wire.
>2.)9V track and the all-plastic track are compatible with one another, you can run Powered Up/Power Functions trains on 9V track just fine (but not the other way around obviously)
If you got a shit ton of track with a bunch of straights and switches and stuff I'd say go grab the missing 9V parts. If all you got is a small oval or something then you're fine just going with Powered Up.