First of all, see the link below for some bike buying advice. What kind of bike are you getting? What kind of riding will you be doing?
1. pedals. My husband is trying to convince me to get pedals with toe clips or even clipless pedals. My experience with these have been negative as my balance isn't great and I feel trapped by the clips.
If you are riding as much as you are now, you will benefit greatly from clipless pedals. Plenty on them in the link below. The increase in efficiency of pedal stroke is worth it alone.
2. suspension/carbon. I'm used to riding a bike with suspension on crappy city streets and gravel, am I justified to continuing to prefer this over a carbon fork?
Tell is more about the kind of riding you will be doing. I can make recommendations from there.
3. shorts. I just wear running capris. would I benefit from actual riding shorts?
Shorts are not as hot. The pad helps to prevent chafing. It's a small investment. Shorts are also made of wicking material and will help keep the girlie bits cool and dry. If you don't want to wear lycra, you can buy baggy cycling shorts. They have a liner with a pad sewn into "cargo" style shorts. Capris and pants can can caught in the chain or drivetrain. At the least, make sure your capris are skin tight like tights and not loose like yoga pants, especially at the bottom. Loose clothing can cause an accident. Shorts buying advice below as well.
4. tops. I just wear tank tops/jackets. would I benefit from riding tops?
I like cycling jerseys because you can put more stuff in the pockets. At the very least I recommend wearing a wicking top and avoiding cotton. As for tank tops, I'm not a huge fan of them for cycling b/c I get sunburned easily. A full jersey also provides a bit more protection against road/trail rash if you fall. Having said that, it's only my personal feeling. Cycling clothing is also cut for the riding position and won't shift around as much as running/regular clothes. YMMV.
I've been known to use my cycling jackets for walking/hiking/outdoor activities. There really isn't a reason you can't use a running jacket for cycling. The only one I can come up with is that sometimes they are cut shorter than a cycling jacket and will ride up in the back. A cycling jacket is cut for "riding" position and not being upright like you are running. If your current jacket is comfortable and works, I'd continue to wear it.