Well, I'll attempt to answer the questions, and hopefully no one answers before I finish this post.
1. Some of this is more of an eyeball sort of thing. With chunkier teas, I try to visually determine how much I need by how much footprint space it takes in your brewing vessel. A lot of teas, and not just the kind that have chunks of fruit and whatnot in them, will not easily fit into a tablespoon/teaspoon.
2a. An electric kettle is a wonderful idea. I actually use this one at work, and its splendid. http://www.bona-vita.biz/products/kettle5.asp
It's not all that large either. It warms about a liter of water.
2b. The tea floating at the top isn't an issue as long as it's been well-coated with water (at least in my experience). Most tea will float, and after it steeps for a bit, will sink. If you're worried it's not becoming moist enough, just poke at it with your finger or a spoon to ensure its properly moistened.
2c. Steeping times and temps vary wildly from person to person, that's why they vary so wildly on sites. Everyone has their own preference, and probably everyone is right. The longer you brew, the stronger it will be typically, though I would stick to the temperature guidelines, at least in the beginning. Some teas will develop undesirable flavors when brewed too hot. As my own general rule, tea can be always steeped cooler, but when steeped warmer, use some caution. The cooler you steep, the longer it will take (think hours). You could steep tea in room temp water, but it may take all night to do so.
3. If you're just getting into loose-leaf, Adagio is pretty decent.
The issue is a lot of the better online vendors are overseas. There's nothing wrong with that, but samples may take a while to get to you. It's just more of an involved process. I'd use Adagio to feel out what areas you might be more interested in and then ask the boards or explore the vendor section to find a vendor best suited for your tea preferences.
Sorry if I missed a question! And for the inevitable typos.
Edit: First round of typo fixes!