Stevia doesn't grow on trees. It's an herbacious perennial. Buy the seeds from a good company and plant indoors in late winter. Move to the garden after all danger of frost is past. Grow in full sunlight, harvest and dry the leaves to use for sweetener.

Here's an article on the topic: https://homegardenjoy.com/site/2017/12/how-to-get-a-poinsettia-to-bloom.html

Lime won't work. If you have mud, you probably have a drainage issue. I'd look into sloping the land more into channels so water runs off or planting more water-loving plants to soak up the extra water.

First, find a spot in your yard that gets full sun. Full sun means six or more hours a day of bright, direct, uninterrupted light. Most vegetable plants need this much light in order to really produce good veggies. Next, get a soil test done at the local garden center or cooperative extension office. It costs about $10 but will save you a lot of money by telling you exactly what you need to add to the soil. You won't waste money adding nutrients the soil doesn't need. Next decide what you want to grow - what vegetables does your family enjoy eating? Grow only what tastes better fresh and what your family will eat. I recommend looking into some free classes at your local cooperative extension or following a blog like Home Garden Joy. Good luck.

I'd put down some gravel or coarse pebbles then add soil. You may also want to work with the areas instead of trying to fill them in. A rain garden would be a great idea in such a place.

You can divide rudbeckia (Black-eyed Susan) in the late fall or early spring. They should be divided about once every 4-5 years.

I add compost in the fall to my raised garden beds, then again in the spring. A cover crop can also help. This is a crop you sow in the fall that grows throughout the winter. In the spring, you just dig it back into the bed and it decomposes into nutrients for the soil.

It depends on the herb. Most herbs can be dried in a dehydrator. I have an article here that might be helpful: https://homegardenjoy.com/site/2014/06/savor-the-taste-of-summer-how-to-dry-fresh-herbs-without-special-equipment.html

I wouldn't top the tree at all - it's not very healthy for the tree. You can trim back some branches in the winter when it is dormant.

They might need to be divided and fertilized. The fertilizer will help. You can buy tablets and put them into the bottom of the container.

Go ahead and cut them back now in the fall.

Fall for both, although I'd wait until winter to cut back roses.