Canal St Martin

The Bastille section is not very interesting - just a little harbour. Best section is indeed near Gare de l'Est: between jardin Villemin and rue du Faubourg du Temple.
Jardin Villemin was infamous for a homeless/refugee camp, but that was 10-15 years ago. It's all very gentrified now.
As for lunch: there are plenty of options from almost any kind of cuisine imaginable, so it's hard to pick one... For French, I liked Les Vinaigriers one or two years ago, it's in the street of the same name close to the canal. A bit pricier, one street further north Les Enfants Perdus is also very good.
For canal-front lunch, options (Hotel du Nord, Chez Prune) are few, less interesting and usually very busy, but they're not bad either - worth a shot if you value the location more than the cuisine.

EDIT: just saw that your guided tour was at 1pm, that's really early since most places won't open before 12 for lunch and it is a 15 min brisk walk from the Canal to the Père Lachaise. Your options could be limited, then.

Consider taking the boat tour through the locks. It is quite interesting.

Balso- Any suggestions for a cafe or patisserie where we can get a sandwich or a crepe? Or should we head down to Pere Lechaise area for our meal before the tour?

Carol- unfortunately we won’t have time for the canal boat tour. The timing just won’t work.

Miznon Canal, 37 Quai De Valmy. Beef Bourguignon in a Pita, Mmmmm.

Thank you brushtim! I looked it up and that looks perfect!