I do not think that the crack in the base gasket surface is a problem. The coolant leaking into the engine is a big problem.
Is the crud in the water jackets corrosion or from using a dirty bucket to fill the radiator.
The damage to the head looks like old damage, not something that has happened 5 minutes before it was last shut down.
Two base gaskets will raise the ports and lower the compression unless a motor builder machined 0.5 mm off the head or base gasket surface and had to use an extra gasket to get the ports and piston to head clearance where he wanted it.
There are guys on a lot of forums that recommend adding another base gasket in an attempt to avoid spending money on porting. Adding a gasket or doing the correct modification to the ports will produce entirely different results.
Crack in the base gasket? Gasket came off free with no breaks? What makes you say its loses coolant?
The crud felt like sand not dirt, So dont know what that would of caused other than problems! I do know the old owner used to ride it on beach's so more than likley that!
The speckled dark spots in the bore are rust that has been polished off after running. The bore also shows polishing that results from water getting in it while it is running and or there is not enough oil in the fuel. The glue on the head gasket is usually a sign that the previous owner was having head gasket problems and thought it could be solved by using more glue instead of machining the gasket surfaces or getting all of the head bolts where they will hold torque.
The rings are also worn out. Look at all of the brown streaks up and down the cylinder that align with the port bridges and near the piston ring end gaps. The brown streaks are blow by past the rings.
A two stroke is suppose to smoke. If it is not smoking it is not getting enough lubrication.
The areas in the intake port where the iron sleeve is showing because of porting is nothing to worry about.