Some forgers still active:
https://explorer.horizonplatform.io/?page=graphs&graph=forgers

Has a github repo (just forked to save it for the future):
https://github.com/NeXTHorizon/hz-source

Exchange? It has a built in asset exchange... It needs only a gateway Asset to NXT AE and it is possible to buy/sell it. It isn't an impossible mission to write a robot Maybe next week...