THE 100TH CONGRESS IS FULL OF PARTISAN RISK
LEAD: AT the outset of the 100th Congress last week, the leaders tried to strike a bipartisan chord. The new Democratic Speaker, Jim Wright of Texas, told the House of Representatives, ''We seek not confrontation but cooperation.'' At almost the same moment, Bob Dole of Kansas, the Republican leader in the Senate, was saying, ''It is necessary that we start off on a totally nonpartisan, bipartisan basis.