That fuel tank situation is a problem. If it were my bike i would start there. Then proceed with your additional problems. Gotta sort the dirty fuel issue out first.
A tip, I've had to clean a couple maxi tanks and one was terrible. I ended up putting two utility hooks into the garage ceiling and hung the frame by ropes. This allowed me to really get a good shake without my arms tiring out. I like vinegar and rock salt it really helps to scrub and knock that rust loose. Just takes some extra effort to get it all out.
Bottom line dirty fuel = poor performance.