A full answer to your questions is quite involved so here is my abreviated suggestion. Start by figuring out what you need your ground tackle to do. What is the maximum wind speed (I would recommend sizing for a big squall at least)? From this, you can look up the predicted loads on the ABYC recommended loads chart. Will you spend the night at anchor? What are the bottom types you will be encountering?
A logical component to figure out first is the anchor. You already have 2 anchors that are of a decent design. Bruce anchors tend to set well in most bottoms and stay set if the direction of pull changes but their holding power is very low for their weight. The smallest bruce that I would want to use in a bad squall on your boat would be 33lbs. If you decide that you need to purchase an anchor with more holding power, I would recommend either a Manson Supreme or a Fortress. The manson supreme has very good holding power, sets in almost all bottoms, stays set in a veering situation and a 25lb anchor would be great. The fortress has the highest holding power to weight ratio but only works well in most mud and sand bottoms and will not stay buried if the wind shifts making it inappropriate for overnight anchoring.
Connected to the anchor you need some length of chain. The only reason to make the chain really long is if you live in a place with coral or something else that will chafe a line. Otherwise, a good rule of thumb is to have the same length of chain as your boat is long. For your boat, 1/4" G40 or 5/16" BBB should have enough strength. Good shackles are also important.
Then you need line attached to the chain. 1/2" or 9/16" line should be fine for the scenario of a severe thunderstorm. Either 3 strand or anchorplait will work just fine for this. You need adequate scope (5:1 or greater) for the deepest anchorage you ever plan to use at high tide.
On deck, a single cleat is fine provided that it is sufficiently large and well attached. The most important thing is eliminating chafe which is a combination of good chafing gear and well setup chocks. Tubular webbing works really well for chafing gear.
For comparison, I have a 30' full keel sailboat without a windlass and use a 35 lb manson supreme with 30' of 5/16" G40 chain and 250' of 5/8" nylon rode. This has worked in thunderstorms and tropical storms with sustained winds up to 50 knots and gusts up to 70 knots.