Turbo brand products are overpriced. You should get a PC Engine setup, ideally a Duo R or RX system, which will play 97% of the worldwide library right out of the box.
You should also get a TurboEverdrive and try games before you buy. Same deal with CD titles, just burn a cdr and decide if a game is worth owning.
You'll have to mod a system to get RGB output, but it's easier than ever now with dedicated parts and several people who offer the service.
A Duo R or RX will play American games out of the box? Or would I need to do a region mod? I've never done something like that in all honesty. Also, to play cd games I've read something about needing some kind of system card? I'm not very clear on the details.
With the Duo R or RX, you can play all import Hucards with exception to SuperGrafx games, which there's only 5 of. You can't play US Hucards unless you mod the Duo R/RX. There might be an adapter to play US Hucards, but I'm sure it's hideously expensive.
As for CD's, you can play most import & domestic CD's in the R/Rx, with the exception of a few. Games that are labeled as Arcade CD games(Fatal Fury 2, Strider, Mad Stalker, etc.) are only playable on the R/RX IF you have an Arcade system card(either the Arcade Duo or Arcade Pro, but you don't need the Pro unless you get a regular PC Engine/Turbo Grafx setup). Also, there are a few older CD games that have problems running on some systems(Altered Beast).