Moab is awesome, you'll have a great time!! I spend a lot of time there every year and have some suggestions and probably too much info for you lol...
1. Get the "Charles Wells Guide to Moab" book. It will list the majority of the trails with locations, distances, trail markers, difficulty ratings and other info that will help and has pictures of trails and obstacles to help keep you on track, some of the trails can be difficult to follow and its pretty easy to get turned around your first cpl times on a trail. His difficulty ratings are based on stock to mildly built rigs so i would think you could follow his recommendations pretty closely as he's pretty conservative with them (his estimated times to run the trails is always high, especially if its just one or two trucks, we can usually cut his times in half).
2. Get some rock sliders on your rig before you go!! (didnt look at your build thread, disregard if you already have them lol) Moab trails ALL have ledges that you will have to climb or drop down with no bypasses, if you are stock height or close to it, you will be all over your lower rockers even on some of the easier trails. Seriously, if you like your rockers being straight, get sliders.
3. Air down. The difference in traction you get in Moab from running low tire pressure is crazy. With my beadlocks i usually run between 6-12 psi, without beadlocks i would run something around 15 psi or so, it will help tremendously without having a locker. Can be kind of annoying if you dont have a portable air source and are driving back to town on low pressure but i've done it a million times if im not driving 20+ miles out of town on pavement. I carry a powertank with me but pretty much air down day 1 and air back up before we leave town, exception being if I'm running a trail thats really far away like Elephant Hill or something, then i'll air back up for the pavement trip.
4.Spinning the tires isnt a bad thing, when the tires start to spin, stay there and let them work for a bit. The slickrock is real "chirppy" and usually has a little bit of sand on it, tires like to spin alot if you dont have lockers and real low gearing. When they start spinning, work the wheel back and forth and let the tires get warm, alot of times after 10-20 seconds of spinning you will get traction and start climbing again. Be careful though, its easy for the front end to come around sideways when the tires are spinning and you're stuck on a climb as the front end gets light, seen a few flops caused by this, so keep the spinning slow and controlled, youre just trying to get the tires warm and grippy and move some of the small sand and dust off the rock to get you traction.
5. Pack a cooler and bring lunch with you on the trail. Like mentioned before some of the trails get pretty remote, bring lots of fluids/water (and chaptsick!!), its the desert and you will get dehydrated quick even though it wont be that hot during that time of year, and pack a lunch at a minimum, we always bring enough food for dinner also just in case you have trouble and get stuck out there longer.
The three trails you listed are good choices for your first time out. Fins and Hells are in a "fee use area." Its cheaper if you have cash instead of a card, and you can buy a multiple day pass if you arent going to do both trails on the same day. If you are wanting to get more trails in, you should have time to add at least one more on the day you do Fins if you dont sleep in until noon!
Fins is probably the easiest trail in Moab that isnt a dirt road but is great for "getting the feel" for the slick rock and some of the angles/steepness/tippyness that you will experience out there. Should only take a cpl hours at most to run the trail and that accounts for going slow and taking pics and stuff.
Top of the World isnt bad at all, most of it is dirt/rocky road with a few ledges to get over once you start the climb to the top. The view at the top is unreal. Its not a 12hr day to get up and back but can take most of the day if you're taking your time.
Hells is completely doable in a stock rig if you dont attempt the big obstacles. Momentum is key to alof of Hells Revenge...not speed, momentum. Where rigs without lockers have trouble is when they are trying to climb and lose their momentum then try to get moving again and the tires just chirp and spin and they have to back off and try again.
Kane Creek is another fun one in mild vehicles as it has a TON of water crossings and sand washes to play in, however I hadnt been on it in years until this past Thanksgiving when i was out there on my dirt bike and the ledges on the "exit" have gotten pretty big and dug out, might be a bit much for a "stockish" vehicle without a locker, if you attempt that one I would walk the shelf road that starts climbing the canyon at the end and check the ledges before going up to make sure you are ok doing them, theres a pulloff on the right as you start to go up the shelf road where you can park and walk up.
I would recommend checking out the area around Gemini Bridges/Gooney Bird rock, fun and scenic area with lots of trails to explore and its only 10ish miles north of Moab. Porcupine Rim, Secret Spire, Tusher Tunnel, Longs Canyon, Hey Joe Canyon, and/or anything else up along Hwy 128 north of town would all be great areas to check out before you get some lockers/armor/more rigs to go with you.
Grab a burger at Milts, eat some breakfast (they serve it all day) at the Moab Diner, and go see the guys a M4O (Moab 4x4 Outpost) if you run into any trouble with your rigs, they are great guys and always willing to help without bending you over! They even have a "trail recovery" gig which isnt cheap but in an emergency can help get you back to civilization.
I could keep going on and on about that place, one of my favorite places on the planet, but I'll spare you lol.
