part 1: MOV, REP, and ATK are all composite numbers, based on the relavent stat(spd, rep, and pwr) combined with skills, armor, weapon strength, and other equipment. For ATK, this number is simply an addition of pwr + weapon strength + any equipment(skill bonus goes into pwr directly). The other two are more complicated, and involve several hidden variables.
part 2: Speed is your initial quickness, which is then adjusted by various factors, such as the armor you wear or the speed of the weapon being wielded. Movement is the resulting number from that calculation. This is why someone like Futch, who has high speed, can go well after someone with a lower speed.
part 3: There are several factors, as mentioned above. In general, the lighter the characters armor(lightest to heaviest: tunics/robes/leather/chainmail/full armor) the faster they will go. Having a high speed will help, as does improving a characters swing and holy dash skills. However, at the end of the day, the largest factor controlling how fast a character will go is their weapon's weight, a hidden variable inside the game(generally the bigger the weapon, the heavier), a factor which cannot be modified. You can learn more about the swing skill, holy dash skill, and weapon weights by checking out the multiple hits in depth guide here at suikosource.
part 4: Pdef or physical defense is blank for most characters, because the game assumes they will be wearing armor, from which they will draw their defense stat. However, for the three beasts, and the 5 dogs, this statistic actually does increase, since they cannot wear armor.
Unfortunately, there isn't any real record of how exactly all the statistics work in this game, and the data that is there is in several different places. Here's a few basics I can think of(although I don't know all the details)
Skill affects accuracy for sure(and is boosted by the accuracy skill), but it may also be involved with counter attacks and critical hits.
Rep affects your ability to repel attacks, and is boosted by the repel skill
Luck affects stuff, but it's not at all clear what, and to what degree, it could effect critical hits, counter attacks, dropped items, treasure chest finds, corpse finds among others, however nobody is really sure.