Honestly the only reason to skip moissanite is if you specifically want a natural mined diamond for emotional or family reasons. Otherwise it is the best value in jewelry right now.
A 1ct moissanite looks slightly LARGER than a 1ct diamond because moissanite is less dense. A 6.5mm 1ct diamond is about the same visual size as a 6.5-7mm moissanite. In practice the difference is tiny but moissanite wins slightly on face-up size.
Yes, moissanite rings can be resized as long as the metal band is plain gold, platinum, or silver. The stone itself is not harmed by normal resizing. What cannot be resized: full eternity bands with stones all around, and very thin tension settings. Cost is 30-80 dollars.