Sperati - Welcome to SCF!
While I hardly regard myself as an expert

, as stampgal indicated, I am also interested in collecting engraved stamps. I have posted images of some of the stamps in my collection in the Topicals section, particularly in stampgal's "Collecting by Engraver" thread. Please join us in the fun of sharing our scans and knowledge there.
In reply to the specific questions you raised:
1. The following abbreviations sometimes appear in the corners of the lower selvedge or in the design margins on engraved stamps:
del. =
delineavit (Latin) = drawn or designed by (the stamp designer's name).
sc. =
sculpsit (Latin) = carved, or engraved, by (the engraver's name).
2. The engraver's name is
customarily placed on the right, but by no means always! Some postage stamp catalogues identify designers and/or engravers. Also, after a while at this, one gets to know who the engravers are.

3.
Fundamentals of Philately, by L.N. Williams, 1990 Revised Edition, published by the American Philatelic Society, is an excellent reference guide to intaglio engraving, and indeed to all other aspects of stamp design and production.
- nethryk