Have you check out the tips and tricks on the strategyfirst forums?
http://www.strategyfirst.com/forum/s...ad.php?t=35010
I personally never play the rebels.
But as for the weight carrying capacities. After each battle I load up my mercs so they are atleast a few percent over 100 %. Then I have them lie in prone position and use the Record button and have each one of them run back and forth until the record total is about 1000 for each merc. If you do this training, eventually their strength and agility goes up. I wrote in the tips and tricks that you can do this for raising heavey weapons skills and throwing skills as well. By the time I'm near the end of the game my main character can throw almost as far as a Vog launcher.