epitope prediction/ mapping
An expression vector is a (usually circular) piece of DNA which is able to replicate inside a (bacterial) cell independently of the genome. Vectors can be transferred between bacteria and can express proteins from their own DNA sequence. They are used to express proteins inside of bacterial cells which can subsequently be purified. In this case the sequence for an immunogenic peptide is cloned into a vector and expressed in bacteria.
These are antibodies which are directed against a certain peptide. This is one technique of generating these antibodies. Making a (synthetic) peptide and then immunize animals against it. Then you can purify the antibodies from the serum of the animal.
Yes. You make short peptides of 8-12 amino acids (which is the length that the antibodies binds to) and use them for immunization.