Mollylou, depending on where you are, Caladiums are perennial. There is one in my yard that was here when I moved in 4 years ago. Most websites will say they are hardy down to zone 9 or 10. If you were wanting a year-round houseplant, look for a syngonium, which is a trailing plant with Caladium-like leaves, although I don't think they come in that beautiful reddish/pink color. Caladiums need some sun and especially like morning sun. If your plant has been inside for months, that's not enough light. Color and variegation commonly fade on plants that are not getting enough light. If you have a place outside where it can get some sun before noon, you can leave the plant there until light frosts cause the leaves to drop. Knowing where you are would make storage (or possibly perennializing) advice easier. As mentioned, it's natural and normal for them to go dormant for the winter. The white fuzz is probably related to decomposing organic matter in the soil and will probably go away if you let the soil dry out more fully before watering. With so little light and such cool temps, the bulbs are probably using very little water.

I doubt you killed your clematis, but you may have cracked the fragile stems at the base. Keep treating the roots like they are alive and you will probably get new shoots coming up. Best practice is to prune the clematis back hard before you plant leaving only about 6 inches of growth or taller so you have a few sets of leaves. There isn't a leader vine. Sweet Autumn grows fast, so keep watching it so you can try to guide the stems. I add bone meal the way Chalk Hill recommends, but it isn't required. I don't take out the supports that came in the nursery pot unless they fall off. I try to cause as little disruption to the roots as possible. I do take off the twist ties though and use my own. Tightly tying the vine to your support isn't good. I use velcro straps to hold the vines in place. It doesn't take long for the tendrils to grab on, so as soon as it does, the straps can be removed. What I try to do when planting a new clematis is plant it at an angle towards the support. That way the vines will already be growing in the right direction. To help it along, I might add a couple of lengths of thin bamboo on either side of the root mass and use these to help guide the vine. It also serves to protect the vine (somewhat) from dog feet. Where practical, I will use the velcro pieces to hold the bamboo to the support, but most of the time it can just rest on the support because the soil holds it in place.

Even with pics, it's impossible to rule out other things but this looks like a plant that is struggling with the difference in soil between its' peaty root ball and the surrounding soil. This just happens sometimes, despite anyone's best efforts to plant and then coddle them well. Combined with a little frost bite, it's had a struggle. Looks like it's on the frontier, the edge of the bed, and may have been more affected by the frost because of that added exposure. Try not to water it unless it's truly thirsty. That will give it cause to make roots beyond the peat ball. Having long-term mulch there is good. You might have to dig a little deeper, push it back a little bit to give tiny new plants like this room to breathe, but the soil under there should be very nice, well-drained, more fertile, not drying as quickly, moderating temp extremes in summer and winter, a great thing. Replace as needed, as it decomposes, to keep a 2-4" layer of fresh on top. I wouldn't see any need to fertilize these plants. Coleus have always grown well for me without it, especially in the ground. At this point, if you remove the big, mostly damaged older leaves, you'll end up with much nicer looking* plants with many more branches and total mass of foliage. From this angle, the ones I'd remove have orange stars on them, and any others that are more brown than green. The dead parts are just blocking the light. This will allow light to reach more parts of the plant, improve air circulation, and encourage many new tips (which will soon be branches) to grow away from the main stem. I prefer this over pinching the tips on new plants this short, as there is no reduction in height, and the difference at the end of the year is astonishing if done vs. not done at all, and between tip-pinched vs. removing the original leaves from the main stem but not the tip. Glad you find it helpful, I love babbling about one of my fav plants! *Sometimes one might want a tall, thin plant, which is fine. Just trim nothing at all.

Another lesson from this is not to plant seedlings right on top of each other. If you put six seeds in one hole, as it appears you've done, you're going to have six plants coming out of that hole, each of which would fill that whole pot and a lot more. That will make separation of the plants without damaging the roots very hard to do. The roots of your plants are all tangled up. If you plan to put a bunch of plants in one pot, with the idea that you're eventually going to separate them, at least spread them out. I suspect that they're so tangled up that separation won't be smart. Snip away.