Go ahead and use table sugar -- it'll work fine to carbonate your beer.
However, 250g seems high to me. This online calculator suggests that 4.6 oz, 130 grams is the right amount, assuming 12 oz bottles.
Your main concerns when adding the priming sugar are sanitation and proper dilution/distribution. If you don't ensure that the priming sugar is properly mixed with the beer, some bottles may carbonate more than others. The differences could be very dramatic.
My technique for bottling is as follows.
- Measure the sugar using an accurate scale
- Put sugar in a sauce pan and add enough water to barely cover.
- Bring to a boil. Simmer, covered, for 2 minutes.
- Pour the sugar syrup into the bottom of the bottling bucket.
- Rack the beer from the fermenter into the bottling bucket.
- Bottle the beer.
With this technique, there's no need to stir as the turbulence from the racking process is sufficient to distribute the priming sugar solution.
When racking the beer, try to avoid splashing it. This incorporates oxygen and can lead to premature staling. (But since you're bottle conditioning your beer, this is less of a worry since the yeast should consume any introduced oxygen.)