This is probably very simple, but I can't find the command.

I want to lookup a value in an Employee's record while on a Custom Record.

How can I

a) find the id value of the current logged in user?

b) find the id value of an employee via a Record/List field of the Employee on the current record?

If I manually enter an employee id into the following script, I can view the Travel Approval Limit, but I want to retrieve the employee id dynamically.

alert(nlapiLookupField('employee',xxxx,'custentity_travel_approval_limit'));