Your frame has an integrated hanger.
Your current derailleur is a long cage. If you replace, get a long cage.
As noted, Suntour is no longer in business, so if you want indexing you need to get new shifters as well to match the derailleur you buy. You could perhaps find one the same as yours on e-bay, but that's going to be a lucky find.
I seem to remember that some Suntours could be mounted so that they had no tension. The fix was to remove it and wind it up then put it back or something like that. It's been years since I've seen it.