There are numerous resources on the internet that discuss oligonucleotide chemistry, properties, design, etc.-you can just do a search to find what you need most of the time. However, you may want to check out these web sites to start:
http://alces.med.umn.edu/rawprimer.html : Primer design
http://www-genome.wi.mit.edu/cgi-bin/primer/primer3.cgi : Primer design
http://genome-www2.stanford.edu/cgi-bin/SGD/web-primer : Primer design (best one for sequencing primers)
For information on MW, and oligonucleotide conversions, check out http://www.basic.nwu.edu/biotools/oligocalc.html : which we use routinely.