Should you bring your own bins and ´scope?
Absolute minimum is your own pair of binoculars.
Although your Guide will have a pair, (and usually a 'scope as well), it's always best if you bring your own, as if you're using his, he's going to have a hard job finding you the birds. A 'scope is not always essential, but it certainly comes in handy on the Plains of the Alentejo as well as in other situations.
A decent Birding Field Guide will make your holiday that much more enjoyable and we recommend Collins Bird Guide (2nd edition) ISBN 978-0-00-726726-2.
For Dragonflies we recommend Dijkstra and Lewington's "Field Guide to the Dragonflies of Britain and Europe", ISBN 0-9531399-4-8, or, even better, Smallshire and Swash's "Europe's Dragonflies", ISBN 978-0-691-16895-1
For Butterflies we recommend "Butterflies of Britain and Europe" ISBN 978-1-4081-0474-3
For Flowers we recommend Blamey and Grey Wilson's "Wildflowers of the Mediterranean", ISBN 978-0-7136-7015-8