I personally like talking Jewish geography, funny stories that happened to us and what we want to name our kids (jk!) on the first or so date. Then there’s always the topics of camp, school, jobs, family, etc.
Some people progress and get more comfortable and serious faster than others. A lot of times its good to play by ear. Of course topics should get deeper and more serious as time goes on. That also helps further a developing connection.
In terms of length of dates, I dont think there is a rule. I think that 1 1/2 to 2 hours is ideal for a first date, unless of course its going very well-my cousin got engaged after a 14 hour first date! Not typical but it worked for her 🙂