What's your question? Ask

Although not always typical, annual lobelia does occasionally have the propensity to self-seed under good growing conditions. To alleviate this, simply cut off the blooms once faded.

Yes, you can trim the plant back by a third.

Lobelia is an annual plant, not suited to living in a house. It is possible to save the seeds, though, and start them in the spring. Your plant may also have small plantlets growing from the base that can be started as separate plants. These articles will give you some more information: https://www.gardeningknowhow.com/ornamental/flowers/lobelia/lobelia.htm
http://www.gardening.cornell.edu/homegardening/scened819.html

This article should answer your question: https://www.gardeningknowhow.com/ornamental/flowers/cardinal-flower/growing-cardinal-flowers.htm

Though ericaceous compost is ideal for acid loving plants, your lobelia should be just fine.

https://www.gardeningknowhow.com/composting/basics/ericaceous-compost-info.htm

Yes, lobelia does attract bees, and specifically so with Great Blue Lobelia (Campanulaceae).

For more information on lobelia, please visit this page:
https://www.gardeningknowhow.com/ornamental/flowers/lobelia/