yea I don't think there's anything wrong with moving them constantly from indoor / outdoor. (Just make sure the temperatures don't fluctuate too much or you're gonna get thin stretched out plants.)
I do this as well, to save energy, but mainly because the sun is more powerful.
Of course it's gonna feel like your plants stopped growing when you bring them indoors if you have them under CFLs or some shitty lights.
Just make sure you've got drain holes in those cups, and if you leave them outdoors, depending on the weather and temp you will have to water more and don't ever let the soil dry out completely when they're that young.
Oh yea, what soil are you using? At 2 weeks mine are a bit bigger. You can try giving it some weak plant food like Liquid Karma which is .5 - .5 - .1 or another brand but I use Liquid Karma cus they give out free samples of these like candy. I've found that if you add some really low NPK (and I mean really low ratio like Liquid Karma), to the soil after you drop the seed in, your plant will have a really healthy start and growth spurt as soon as it germs.
Yea it looks normal. leaves start out small and get bigger as the plant grows. Sometimes you may have deformed leaves due to nutrient problems or genetics though. I planted 8 nirvana WW and 1 has these giant fan leaves that are 3x bigger than all the others. Pretty weird. May be a male.
This will be their first intro to nutrients. 
