Lights - You dont say what kind of lights you are using. Most of the people on this forum are using standard shop lights with t12 or t8 bulbs and 3-4 inches from the lights is about right. Check with the "growing under lights" forum if you have high powered lights.

Timing - Its generally better to plant out your plants when they are young than having them in the pots to long. The longer you have them inside the more likely they are to get stressed out in pots that have become to small for them. If you start earlier definitely plan on transplanting them a few times.

Transplanting - Its better to transplant seedling early if you are sowing in group containers. the longer they are in there, the more the roots intertwine and the more damage you do when dividing them. When they are starting the second set of true leaves is the standard time - I do it after the first set of true leaves. They will grow just fine in the Jiffymix- thats not a problem, I wouldnt use potting soil, but some people use potting mix in the bottom half of containers. A lot of this will depend on what you are growing (you dont say) Most seeds will germinate just fine in a decent potting mix. I only use the extra fine jiffy type mix for tiny tiny seed.

Tools - It has never occurred to me to buy a tool for planting seeds. I use pieces of old window blinds (even a new set is probably cheaper than the tools they sell). Cut in to pieces with the ends rounded off or cut into points, they are great for managing the small seeds, and the rest are cut up for markers. Longer pieces work well to lift seedling out of the six pack cells that I use sometimes. Very versatile and free.

People handle all of this in at least a dozen different ways. Ultimately you have to figure out what works best for you.

Here my observation. I will start the seeds in cells, could be moss cells or plastic cells. This makes transplanting them to 4 inches pots simple and easy. These seedlings are so fragile and if you are not careful during the transplanting you lost them.

If you hold your hand under the light palm down, and the back of your hand is not warm, the lights are not too close. I've had plants growing around the bulbs without hurting them.

Mike