1) My rosemary is in a pot with no drain hole (I put rocks at the bottom before potting soil), and I've noticed the plant becoming more and more "stalky" and the leaves thinning out more and more. Its loosing the robust smell it once had too.

You need drainage. Transplant to a pot with a hole or holes, then get a basin to catch the run-off. You can put the pot on top of rocks in the basin if your plants get rain so the soil doesn't stay soggy. You can prune all your plants to encourage bushier growth - pinch off with your fingers or use good sharp pruners or scissors. As rosemary gets older, I have found it to get woody and lose it's fresh smell too.

2) All the leaves on the bottom lower half of my oregano died off.

This happens with mine too. Trim the yellow leaves. Yellow leaves can mean lots of things - too much/too little water, not enough nitrogen.

Now the plan is top heavy and causing stalk problems.

Again, pinch for more sturdy growth. When you pinch back, the stalk tends to fork into two branches, making a more bushy plant.

3) My red pepper plant constantly gets these little white bugs and giant red ants are crawling in the soil.

Find an organic spray for your plant, or check out the Pest forum for a home-made variety I have seen posted here frequently.

4) How do you harvest herbs from the plant with out harming the plant or the stalk?

Pinch only what you need. Unless you want to be able to harvest for drying, in which case you will likely need many plants.

For whoever is taking the time to read and respond. I really appreciate it.