How many poles and how far apart are they? I would plant 3 seeds per pole, if the poles are 6-10" apart. You may also plant 5 seeds per pole and if all germinate, cut 1 or 2 at ground level.

Be sure you have enough drainage holes in each half. I grow in half whisky barrels that are about the same size and drill six holes in the bottom as well as four to six holes on the sides about 2 inches above the base. When I had fewer holes, I had problems with soggy soil in the bottom.

We don't know how big your 'starter pots' are so we can't say how many seedlings should be in each. However, think about the size of the mature plants and how many you will need of each. Sage for example will grow into a perennial low shrub and most people don't need more than one plant if its purely for culinary use. So you can thin out almost all of the seedlings. Cilantro on the other hand is a short lived annual which is used by the fistful. You need lots of plants and you need to repeat sow all through the season. Oregano is also a perennial sub shrub and spreads. One or two plants would be sufficient for most people. Mint, another perennial is also something you only need one or two plants of. For parsley three or four plants would probably suffice and that would be for someone who uses a lot. (It's biennial so you need to so every year). And as for the Alpine strawberries - you can never have too many since the fruit are small. All the perennials will transplant easily into larger pots as they grow. Cilantro transplants poorly and it is likely to bolt. Parsley too, on account of its deep tap root is not a great transplant candidate.

No one seems to have answers for you so I'll give you my thoughts. Container planting for veggies isn't one of my favs for suggestions, never had much success with that method other than possibly a small cherry tomato plant for minimum production. That being said, a max of one plant per 5 gal container is your best bet, I say this because later on when the pepper or sweet potato plant grow large it will keep you pretty busy watering the plants. Also black containers aren't the best color as they will get very hot in the summer sun and roast the roots on the inner wall, so it's best to shade the container portion. And 25 gal containers? would not like to move those when the time comes. Sorry for the dismal report, just too used to planting veggies in the ground where moisture, temperature, and daily attendance is less cumbersome (though weeding part is easier). Good luck!