LePan11 Andriod tablet. Basic Info Needed

:confused: Hi folks. Being a complete novice to tablets, androids and "ice creams", I'm hoping someone could be kind enough to answer a couple of questions.

1 I am amassing a large number of 'logout-xx.srf' files. xx at the moment in #36. Can you tell me what these files are for? about? and can I delete them?

2 I also get 'downloadfile-3.txt' files. again, Can you tell me what these files are for? about? and can I delete them?

3 Can you suggest a book that would give me the basics of working with an adroid device.

thanks for any help you can give.....jackie