Is it normal, ya sort of :) Not real world results, but it gives you a number for comparison between other devices. Its sort of like car performance and fuel economy results, they are test track and not real world results if that makes any sense.
32gb is the unformatted size, so figure a loss on average of about 74 megabytes (MB) per GB for formatting, basically 32 x 74mb, is about 2.368 gigs, and 2.368 subtracted from 32 = 29.632 but close enough to your 29.71GB number. It may vary slightly on different devices like sticks, drives, etc, depending on what they need for overhead. As far as the speed tests, that really depends on the type of file you are reading or writing. Tiny files in short bursts will give you a different result than reading or writing a 5 or 10gb file. I think the stated 40 mb/s speed is an average of whatever mixture they test on these devices. The chances of hitting that speed is probably not going to happen. What you seem to be averaging is about 1 meg a second write and 2 megs a second read speed, so a 10 meg file would take 10 seconds to write and 5 seconds to read with the data that you used for testing. Hopefully that helps.
Yes. Good at saving a lot more information but does not generally speed up the Nook overall speed. So get a larger capacity card like this for more storage space, not tablet performance. Devices have separate memory built into the devices For operation which are not upgradable.
This is a class 10 SD card which is printed very small on the card as a 10 inside a "C", like this @. Class 10 is basically the highest class. The class mainly refers to write speeds when saving to the card, but is supposed read a little faster, too. Write speed is most important for HD video recording.