To see how much cycles are in a canister you can do dfx canister --network ic status <canister id>. You can do that for all the canisters you control.
The biggest drain on cycles at the beginning is probably the creation of new canisters: Just creating a canister costs 0.1T cycles, and dfx by default uses 4T cycles to create a canister (therefore the canister ends up with 3.9T cycles after creation). If you want to create canisters with less cycles, you can use the --with-cycles flag when creating the canisters.
There is no central registry of deployed canisters. But in your project (just next to dfx.json there should be a file called canister_ids.json that says which canister in your project is deployed under which canister id. You can also use something like icscan.io which will show some of the canisters your wallet created if you search for your wallet’s id. You can figure out your wallet id with dfx identity --network ic get-wallet.