As for your questions:
1) Currently, Terrier offers no support for incremental indexing. However, there is a simple workaround. Basically, you have to index the new content, and merge it with your existing index. Please have a look at StructureMerger: [ir.dcs.gla.ac.uk
2) Nope, but you can implement one by looking up the terms in any given document using the DirectIndex: [ir.dcs.gla.ac.uk
3) From the properties page (http://ir.dcs.gla.ac.uk/terrier/doc/properties.html): TrecDocTags.casesensitive
4) What do you mean by "search for more than one term"? By default, Terrier retrieves documents containing *at least one* of the query terms. If you want it to search for documents containing *all* query terms, please have a look at [ir.dcs.gla.ac.uk
5) Nope. If you really want to do this, you can start by looking at neighbour terms in the lexicon, since these share the same prefix.