Ab rollouts 3-5 sets of 5-10 reps
Russian Twists 3-5 sets of 8-12 reps (weighted on a low decline bench)
V-ups 3-5 sets of 10-15 reps
Back extensions 3-5 sets of 10-15 reps
After your last set, perform one max set of bicycle kicks (chinnies).
Perform the above as a circuit moving from one exercise to the next. Rest 60 seconds and repeat for a total of 3-5 sets
Hanging leg raises
Weighted Swiss ball crunches
Saxon side bends or dumbbell side bends
Supermans or reverse hyperextensions
Same as above. Perform 3-5 total sets done as a circuit. Rest 60 seconds after each finished set. Once you finish your last set, perform a plank hold for as long as you can.
Dragon Flag - 5 reps
Turkish Getups - 5 reps each side
Dumbbell side bends or Deadlift twists
Same as the other days. After your last set, perform a high-rep set of v-ups or crunches.
That should keep you challenged for quite some time. Do a search for exercises you are not familiar with.
Some of those are done with weight (Turkish getups, russian twists, side bends, saxon side ends, weighted swiss ball crunches).
No, using weighted exercises will not make your waist wider. Your waist will build some muscle, but the only reason it will be wider is if you are not lean and have a layer of fat over the abs making you look blocky.
You hold the weight out in front of you when performing Russian twists. Do a search online and I'm sure you'll find some photos or videos showing them being done weighted.
EDIT: Muscle is 1/3 the size of fat. It takes up less space than fat. It's more dense.
Have you seen any photos of an athlete or bodybuilder (non drug using) with their shirt off? They have well-defined obliques and rectus abdominus. The obliques don't continue to grow outward wider than the rest of you. But if you have too much fat over you, then yes, you may appear to be "blockier" or wider.
The muscles will only grow so wide, and as long as the rest of your body is built correctly, it won't be wide, blocky or weird looking. Just don't get fat.