The scope you mentioned is a achromat lens type. They are known for low color correction because the lens is a two element optic. For achromatic lenses this is considered normal. As for the multible images, it could be poor eyepiece quality. Usually refractors never need collimation due to the fact that the lenses are fixed to the tube. Do this...set the scope outside and wait for the tube to cool down. Use the lowest power eyepiece you have (25mm) or so and focus on a star. Try this without the 90 degree diagonal and then with it. See if there is a difference. Usually using higher power eyepieces in a small refractor (70mm is small). Let us know what happens.