I know Congress holds the purse strings. It decides whether to fund or not to fund. Does Congress work within a budget for its own activities? Who sets it?

For example there have been 8 Benghazi investigations. SO FAR.  Did Congress have a budget? Who gave permission to have 8 investigations? Isn't redundancy expensive? There have been at least 60 times  Congress took a vote to repeal the  ACHA . At what cost? Will there be more? Who audits  the amount of money spent by Congress for its own activities?  Does Congress have a  blank check for whatever  it decides it wants to do but has a tight budget  or not budget for anything else in which it has no dog in the fight?