Short answers, pulled from the story.
The Helvetic Republic collapsed on the 19th of February 1803 when Napoleon Bonaparte issued the Act of Mediation. This event abolished the centralized state and restored the cantons to form the Swiss Confederation again.
Peter Ochs, a magistrate from Basel, designed the constitution of the Helvetic Republic. It established a central two-chamber legislature with a Grand Council and Senate, plus an executive Directory of five members that created actual Swiss citizenship for all residents.
The Cantons of Uri, Schwyz and Nidwalden raised an army of about 10,000 men led by Alois von Reding to fight the French. This force deployed along a defensive line from Napf to Rapperswil and besieged French-controlled Lucerne before surrendering on the 4th of May 1798.
By 1802 and 1803 the Helvetic Republic was 12 million francs in debt after starting with a treasury of only 6 million francs. This financial collapse occurred within four years of its founding due to costs imposed on local populations for feeding occupying soldiers.
The Helvetic Republic remains controversial because some cantons like Vaud, Thurgau and Ticino view it as a time of political freedom while others see it as national weakness and loss of independence. The Federal Assembly chose not to celebrate the 200 year anniversary in 1995 but allowed individual cantons to commemorate their own experiences.