Welcome to the fleet, Coaster!

The front beam will definitely support the replacement cleat. You have a few options - re-tap the original holes if they are not too damaged (you mentioned the original cleat "tore" out, but I'd bet there was some electrolysis action there, too); or you can drill and tap the original holes up to the next size bolt that fits through the cams; or you can drill and tap new holes adjacent to the original location. Make sure you use good machine screws - a touch of thread-lock or Duralac is a good idea.

There is nothing wrong with putting a new, longer spin sheet on the boat. Most F18s use spin sheets that are about 50-feet long. I prefer 8mm Robline Racing Sheet. Line is a very personal thing, however - consult with your crew and build that team approach to boat set-up.

Good luck and have fun!