When working on the heli disconnect the motor for safety
First your #1 and #6 go together put all your trims to center except the throttle trim it's all the way down. your servo arms should be at 90* as shown on page 2 of the manual I have linked below. if the arms are not at 90* with trims centered then remove servo arms an reset them as close to 90* as possible and then trim to 90* if you can hook your transmitter up to a computer and it has sub trims use them if not you will have to use the transmitter trims. then adjust links to get the swashplate level. If the heli drifts backwards as you state you need to balance it as you said in #6 when holding the flybar the heli should be level if it's tail heavy it will drift backwards as you noticed. If it still drifts back move the battery foward if you can if not you may have to add some wieght to the nose end to get proper balance
#2 when looking at the heli from the right side the tail rotor blades should turn counter clockwise. the leading edge of the blades should turn from the bottom toward the front and up into the main rotor. If the belt is catching on itself that sounds like it has to many twists in it should be only a half twist. It might take a couple of trys to get the twist in the right direction to get the rotor turning in the right direction. I think if you pull the belt horizontal and twist it to right vertical that might get the rotation direction you need.
#3 make sure you are in normal flight mode switch at top right of transmitter
to check the pitch. page 1
#4 and #7
start with #7 make sure the rudder trim is centered with power on (make sure motor is disconnected no surprise startups) is the servo arm at 90* as in picture on page 5 of the manual if not remove and replace the arm as close to 90* as possible might need trim get it at 90*(usual problem for unequal travel) then check to see if the tail slider is centered again see picture on page 5 if not loosen tail servo mount and move servo along the boom until the slider is centered and test fly and readjust if needed till tail holds position. after this the gyro might need adjusting. I hope this helps as a starting point towards a fix. Other people will step in and add to this I hope I'm sure I missed something