In addition to the responses so far, in your second question you ask about a concentrated boil and topping off with distilled or purified water. Keep in mind that your brewing water should be sanitary, but not distilled. To keep things as simple as possible, you could buy 3 one gallon bottles of spring water at the grocery store and leave them unopened in the fridge until you have chilled the boiled wort to ~100F in an ice bath. Combining that wort with the 3g of ~35F water from the fridge should get you to the point where you are ready to aerate the batch.
A couple other random thoughts:
- The 5 gallon carboy will be a little small as a primary for your second 5g batch. You might want to consider using the bottling bucket for primary fermentation of your first batch because it makes aeration a lot easier and you won't need a blowoff tube. You can also avoid racking altogether with it. Then you can put your second batch in the 6g carboy.
- It looks like you've done a lot of reading and already know a fair amount about brewing, so on your first batch, do your best, keep good notes, and don't be afraid to just wing it. You'll learn a whole lot on your first batch, so you can tweak your system as needed once you've gone through it.
Have fun, and good luck!