So if I bought a r4 card could I not just use that for HOMEBREW and use my Sky3ds for 3ds games.
I don't think that word means what you think it means.
Keep using your Sky3DS to play 3DS games. Homebrew is stuff like NinjaHax and Gateway.
Keep an eye out for DSTwoPlus. That's probably more along the lines of what you mean it to mean. It's just not out yet.
As for playing DS games... yes, stick to using R4i flashcarts. Unless you know where to find an old DSTwo...